Showing papers in "Journal of Zoology in 2011"

Assessing tiger–prey interactions in Sumatran rainforests

Abstract: Little is known about interactions between the critically endangered Sumatran tiger Panthera tigris sumatrae and its prey because of the difficulties associated with detecting these species. In this study, we quantify temporal overlap between the Sumatran tiger and five of its presumed prey species from four study areas comprising disturbed lowland to primary submontane forest. Data from 126 camera traps over 8984 camera days were used to estimate species activity patterns and, in turn, their overlap through the coefficient Δ (ranging from 0 to 1, i.e. no overlap to complete overlap). A newly developed statistical technique was applied to determine confidence intervals associated with respective overlap, which is important, as such measures of precision are usually not estimated in these types of study. Strong temporal overlap was found between tiger and muntjac Muntiacus muntjac (Δ=0.80, 95%CI=0.71–0.84) and tiger and sambar Cervus unicolor (Δ=0.81, 0.55–0.85), with the latter illustrating the importance of measuring precision. According to the foraging theory, Sumatran tigers should focus on expending lower levels of energy searching for and then capturing larger bodied prey that present the least risk. Hence, surprisingly, there was little overlap between the crepuscular tiger and the largest-bodied prey species available, the nocturnal tapir Tapirus indicus (0.52, 0.44–0.60), suggesting that it is not a principal prey species. This study provides the first insights into Sumatran tiger–prey temporal interactions. The ability to estimate overlap statistics with measures of precision has obvious and wide benefits for other predator–prey and interspecific competition studies.

Continuing wildlife population declines and range contraction in the Mara region of Kenya during 1977-2009

Abstract: Populations of many wild ungulate species in Africa are in decline largely because of land-use changes and other human activities Analyses that document these declines and advance our understanding of their underlying causes are fundamental to effective management and conservation of wild ungulates We analyzed temporal trends in wildlife and livestock population abundances in the Mara region of Kenya We found that wildlife populations in the Mara region declined progressively after 1977, with few exceptions Populations of almost all wildlife species have declined to a third or less of their former abundance both in the protected Masai Mara National Reserve and in the adjoining pastoral ranches Human influences appeared to be the fundamental cause Besides reinforced anti-poaching patrols, the expansion of cultivation, settlements and fences and livestock stocking levels on the pastoral ranches need to be regulated to avoid further declines in the wildlife resource

Genome duplication in amphibians and fish: an extended synthesis

Abstract: Whole genome duplication (leading to polyploidy) is widely accepted as an important evolutionary force in plants, but it is less recognized as a driver of animal diversification. Nevertheless, it occurs across a wide range of animals; this review investigates why it is particularly common in fish and amphibians, while rare among other vertebrates. We review the current geographic, ecological and phylogenetic distributions of sexually reproducing polyploid taxa before focusing more specifically on what factors drive polyploid formation and establishment. In summary, (1) polyploidy is phylogenetically restricted in both amphibians and fishes, although entire fish, but not amphibian, lineages are derived from polyploid ancestors. (2) Although mechanisms such as polyspermy are feasible, polyploid formation appears to occur principally through unreduced gamete formation, which can be experimentally induced by temperature or pressure shock in both groups. (3) External reproduction and fertilization in primarily temperate freshwater environments potentially exposes zygotes to temperature stress, which can promote increased production of unreduced gametes. (4) Large numbers of gametes and group breeding in relatively confined areas could increase the probability of compatible gamete combinations in both groups. (5) Both fish and amphibians have a propensity to form reproductively successful hybrids; although the relative frequency of autopolyploidy versus allopolyploidy is difficult to ascertain, multiple origins involving hybridization have been confirmed for a number of species in both groups. (6) Problems with establishment of polyploid lineages associated with minority cytotype exclusion could be overcome in amphibians via assortative mating by acoustic recognition of the same ploidy level, but less attention has been given to chemical or acoustic mechanisms that might operate in fish. (7) There is no strong evidence that polyploid fish or amphibians currently exist in more extreme environments than their diploid progenitors or have broader ecological ranges. (8) Although pathogens could play a role in the relative fitness of polyploid species, particularly given duplication of genes involved in immunity, this remains an understudied field in both fish and amphibians. (9) As in plants, many duplicate copies of genes are retained for long periods of time, indicative of selective maintenance of the duplicate copies, but we find no physiological or other reasons that could explain an advantage for allelic or genetic complexity. (10) Extant polyploid species do not appear to be more or less prone to extinction than related diploids in either group. We conclude that, while polyploid fish and amphibians share a number of attributes facilitating polyploidy, clear drivers of genome duplication do not emerge from the comparison. The lack of a clear association of sexually reproducing polyploids with range expansion, harsh environments, or risk of extinction could suggest that stronger correlations in plants may be driven by shifts in mating system more than ploidy. However, insufficient data currently exist to provide rigorous tests of these hypotheses and we make a plea for zoologists to also consider polyploidy as a possibility in continuing taxonomic surveys.

Cuckoo adaptations: trickery and tuning

Abstract: I suggest that the cuckoo's parasitic adaptations are of two kinds: ‘trickery’, which is how adult cuckoos and cuckoo eggs and chicks evade host defences, and involves adaptations that have co-evolved with host counter-adaptations, and ‘tuning’, which is how, once accepted, cuckoo egg and chick development are then attuned to host incubation and provisioning strategies, and which might not always provoke co-evolution. Cuckoo trickery involves adaptations to counter successive lines of host defence and includes: tricks for gaining access to host nests, egg trickery and chick trickery. In some cases, particular stages of host defences, and hence their corresponding cuckoo tricks, are absent. I discuss three hypotheses for this curious mixture of exquisite adaptation and apparent lack of adaptation: different defences best for different hosts, strategy blocking and time for evolution of defence portfolios. Cuckoo tuning includes adaptations involving: host choice and monitoring of host nests, efficient incubation of the cuckoo egg, efficient provisioning and protection of the cuckoo chick, and adaptations to avoid misimprinting on the wrong species. The twin hurdles of effective trickery in the face of evolving host defences and difficulties of tuning into another species' life history may together explain why obligate brood parasitism is relatively rare.

Leopard prey choice in the Congo Basin rainforest suggests exploitative competition with human bushmeat hunters

Abstract: Analyses of leopard Panthera pardus prey choice reveal a strong preference for species weighing 10–40 kg. In the Congo Basin rainforests, species within this weight range are also targeted by bushmeat hunters, potentially leading to exploitative competition between leopards and hunters. We investigated leopard prey choice along a gradient of human disturbance, hypothesizing that leopards will exploit smaller prey where competition is strong, possibly resulting in reduced leopard densities at highly hunted sites. We determined leopard diet by means of scat analysis at four rainforest sites in central Gabon, which varied according to their distance from human settlements. Camera trap data collected at each of the four study sites revealed that human hunting intensity increased with proximity to settlements, while the abundance of potential leopard prey species decreased. We found no evidence of leopards at the site nearest to settlements. At the remaining sites, the number of scats collected, mean leopard prey weight and the proportion of large prey (420 kg) in leopard diet increased with distance from settlements. Camera trap data demonstrated that leopard population density increased with distance from settlements, from 2.7 � 0.94 leopards/100 km 2 to 12.1 � 5.11 leopards/100 km 2 . Our results document an increasing use of smaller prey species and a decrease in leopard density in proximity to settlements, supporting our hypothesis. Comparison of leopard diet with hunter return data revealed a high dietary niche overlap between leopards and hunters at sites situated at similar distances from settlements. Our results suggest that bushmeat hunting may precipitate the decline in leopard numbers through exploitative competition and that intensively hunted areas are unlikely to support resident leopard populations. Conserving the leopard in the Congo Basin will rely on effective protected areas and alternative land management strategies that promote regulated human hunting of leopard prey.

The evolution of ‘bizarre structures’ in dinosaurs: biomechanics, sexual selection, social selection or species recognition?

Abstract: ‘Bizarre structures’ in dinosaurs have four main traditional explanations: mechanical function, sexual selection, social selection and species recognition. Any of these can be plausible for individual species, but they fail to be persuasive when other lines of evidence cannot adequately test them. The first three also fail as general propositions when phylogenetic analyses based on other characters do not support scenarios of selective improvement of such functions in their clade (or the explanation simply does not apply to any other species in the clade). Moreover, the hypothesis of sexual selection requires significant sexual dimorphism, which has never been conclusively established in dinosaurs. We propose instead that species recognition may have been a more general force that drove the evolution of bizarre structures in dinosaurs. That is, the bizarre structures communicate to other individuals a variety of possible associational cues, including species identification, potential protection and social habits and the appropriateness of potential mates. In other words, bizarre structures amount to an advertisement for positive association. Neither species recognition nor any other hypothesis should be a ‘default’ explanation. Although direct observation is impossible, we propose two tests. First, contrary to adaptive, social or sexual selection, under the species recognition model morphology should be expected to evolve without obvious directional trends, because the only objective is to differ from one's relatives. Hence, patterns of evolution of bizarre structures should be relatively proliferative and non-directional. Second, several contemporaneous species should overlap in geographic range (sympatric, parapatric, peripatric). Fossil species often show evidence of this pattern in the past by ‘ghost ranges’ of related taxa. These tests together could reinforce or weaken an argument for species recognition.

Differential effects of artificial lighting on flight and foraging behaviour of two sympatric bat species in a desert

Abstract: Human habitation in deserts can create rich novel resources that may be used by native desert species. However, at night such resources may lose attractiveness when they are in artificially lit areas. For bats, attraction to such manmade habitats might be species specific. In an isolated village in the Negev desert that is known for its high bat activity we investigated the effects of artificial lighting on flight behaviour of two aerial insectivorous bat species: Pipistrellus kuhlii, a non-desert synanthropic bat, common in urban environments and Eptesicus bottae, a desert-dwelling species. Using an acoustic tracking system we reconstructed flight trajectories for bats that flew under artificial lights [Light treatment (L)] versus in natural darkness [Dark treatment (D)]. Under L both P. kuhlii and E. bottae flew significantly faster than under D. Under L, P. kuhlii also flew at significantly lower altitude (i.e. away from a floodlight) than under D. Whereas P. kuhlii foraged both in L and D, E. bottae only foraged in D. In L, activity of E. bottae decreased and it merely transited the illuminated area at commuting rather than foraging speed. Thus, under artificially lighted conditions the non-desert synanthropic species may have a competitive advantage over the native desert species and may outcompete it for aerial insect prey. Controlling light pollution in deserts and keeping important foraging sites unlit may reduce the synanthropic species' competitive advantage over native desert bats.

Animals traded for traditional medicine at the faraday market in South Africa: species diversity and conservation implications

Abstract: In South Africa, animals and plants are commonly used as traditional medicine for both the healing of ailments and for symbolic purposes such as improving relationships and attaining good fortune. The aim of this study was twofold: to quantify the species richness and diversity of traded animal species and to assess the trade in species of conservation concern. We surveyed the Faraday traditional medicine market in Johannesburg and conducted 45 interviews with 32 traders during 23 visits. We identified 147 vertebrates representing about 9% of the total number of vertebrates in South Africa and about 63% of the total number of documented species (excluding domestic animals) traded in all South African traditional medicine markets. The vertebrates included 60 mammal species, 33 reptiles, 53 birds and one amphibian. Overall, species diversity in the Faraday market was moderately high and highest for mammals and birds, respectively. Evenness values indicated that relatively few species were dominant. Mammal body parts and bones were the most commonly sold items (n = 453, excluding porcupine quills and pangolin scales), followed by reptiles (n = 394, excluding osteoderms), birds (n = 193, excluding feathers and ostrich eggs), and amphibians (n = 6). Most (87.5%) species traded were of Least Concern using IUCN criteria, although 17 species were of conservation concern. However, a higher than expected proportion of traders (62.5%) were selling listed species, which is a matter for concern and should be monitored in the future.

Brown bears possess anal sacs and secretions may code for sex

Abstract: Olfactory communication occurs in carnivores and many scent-mark with anal gland secretions (AGS), which contain a variety of information including sex-related cues. Currently, there is disagreement about whether bear species, other than the giant panda Ailuropoda melanoleuca, possess anal glands or anal sacs. We documented anal sacs in brown bears Ursus arctos and analyzed AGS from 17 free-ranging, sexually mature individuals using gas chromatography–mass spectrometry. We hypothesized that brown bear AGS codes for sex, as it does in giant pandas, and predicted that AGS shows sex differences in gas chromatogram (GC) profiles, number of compounds, the digital and analog coding of chemical compounds, and color. We found 90 different compounds. Our results support the predictions that male and female AGS differs in GC, analog coding and possibly color. However, we found no significant difference between sexes in number of detected compounds or in the digital coding. Our results confirm that brown bears possess anal sacs, that secretions likely relay information about sex, and suggest other chemical information critical to the bears' social system is encoded in the AGS.

Diet determination of the Cape Mountain leopards using global positioning system location clusters and scat analysis

Abstract: Studying leopards Panthera pardus in mountainous regions is challenging and there is little ecological information on their behaviour in these habitats. We used data from global positioning system (GPS) radio-collared leopards in conjunction with leopard scat analysis to identify key aspects of leopard feeding habits in the Cederberg Mountains of South Africa. We located 53 leopard kill/feeding sites from clustered GPS locations of ≥4 h and analysed 93 leopard scats. Both methods showed that klipspringers Oreotragus oreotragus and rock hyraxes Procavia capensis were the most common prey. GPS location clusters showed that the time leopards spent at a given location was positively related both to the probability of detecting prey remains and to prey size. Leopards made significantly more large kills in winter than summer (P=0.003); there was no significant difference between male and female leopards in the average number of large kills or the average time spent at large kill sites. We show that, when studying large carnivores in inaccessible areas, it is important to use a combination of techniques to understand their feeding ecology and that GPS locations can be used to provide an accurate measure of diet even when small prey are being taken.

Skull mechanics and implications for feeding behaviour in a large marsupial carnivore guild: the thylacine, Tasmanian devil and spotted‐tailed quoll

Abstract: Extinction risk varies across species and is influenced by key ecological parameters, such as diet specialization. For predictive conservation science to be effective, we need to understand extinction risk factors that may have implicated recent species extinctions. Diet and feeding behaviour of the large extinct marsupial carnivore Thylacinus cynocephalus or thylacine have long been debated. Improved understanding of the skull's biomechanical performance and its limitations in a comparative context may yield important insights. Here, we use three-dimensional (3D) finite element analysis to assess aspects of biomechanical performance in the skull of T. cynocephalus relative to those of two extant marsupial carnivores with known diets that occurred sympatrically with T. cynocephalus: the Tasmanian devil, Sarcophilus harrisii, and spotted-tailed quoll, Dasyurus maculatus. Together, these three species comprised the large mammalian carnivore guild in Tasmania at the time of European settlement. The bone-cracking S. harrisii produced high bite forces for its size as expected, but the stresses induced were surprisingly high. A higher proportion of cancellous bone in the skull of this osteophage may act to absorb shock but decrease rigidity and hence raise stress. A relatively high bite force and rigid skull characterized D. maculatus, which may allow them to target prey of variable sizes. Compared with S. harrisii and D. maculatus, we found that the skull of T. cynocephalus was least well adapted to withstand forces driven solely by its jaw-closing musculature, as well as to simulations of struggling prey. Our findings suggest that T. cynocephalus likely consumed smaller prey relative to its size, which may have had implications for their survival.

Bizarre structures in dinosaurs: species recognition or sexual selection? A response to Padian and Horner

Abstract: Since the mid-1970s, most investigators have agreed that the ‘bizarre’ structures (here referred to as ‘exaggerated’ structures) of dinosaurs – for example, the horns and frills of ceratopsids, the crests of lambeosaurine hadrosaurids, the domes of pachycephalosaurs – functioned first and foremost as signalling and combat structures used in mate competition (Farlow D Hopson, 1975; Molnar, 1977; Spassov, 1979; Ostrom & Wellnhoffer, 1986; Sampson, 1997, 2001; Dodson, Forster & Sampson, 2004). Padian & Horner (2010) argue that the mate competition hypothesis is not supported by available evidence, citing in particular the lack of data documenting sexual dimorphism within dinosaur species. In place of the mate competition model, they present a challenging and novel alternative, suggesting these traits functioned as species recognition features for identifying conspecifics, thereby facilitating social interactions such as herding, mating and parental care. Padian & Horner offer a pair of tests for distinguishing paleontological examples of exaggerated traits evolving under the influence of species recognition from those resulting primarily from sexual selection. The first test relates to the patterns of diversification of exaggerated structures, predicted to be random under the influence of species recognition and directional if driven by sexual selection. The second test invokes evidence of geographic overlap of closely related, contemporaneous species, thought to be a necessary condition for the evolution of exaggerated structures under the influence of species recognition (in part so as to avoid unwanted matings). These authors argue that known examples of exaggerated structures among dinosaurs pass both of these tests, indicating that species recognition is the preferred (though not necessarily sole) explanation. Padian & Horner highlight a major problem common to most previous studies addressing the function of dinosaurian exaggerated structures – lack of phylogenetic context. Comprehensive testing of adaptation hypotheses requires mapping of relevant characters onto independently derived phylogenies in order to search for evidence of evolutionary assembly of the purported adaptation. They also underline the importance of assessing the full range of alternative hypotheses as rigorously as possible, rather than accepting one explanation as the default. We fully support both of these contentions. Nevertheless, we disagree with several of the paper’s central conclusions, including: (1) the necessary correlation of overt sexual dimorphism and sexual selection; (2) the required linkage between sexual selection with a directional pattern of diversification; (3) evidence for the geographical overlap of multiple closely related dinosaur taxa bearing exaggerated structures. In addition to countering these claims, we propose two alternative predictions that allow putative species recognition traits to be distinguished from sexually selected ones. With regard to the exaggerated structures of dinosaurs, the species recognition hypothesis fails both of these tests, and the sexual selection hypothesis remains by far the best-supported explanation. Citing Darwin (1871), Padian & Horner claim that sexual dimorphism is effectively the sine qua non of sexual selection. They argue further that the apparent absence of sexual dimorphism in dinosaurian exaggerated characters is Journal of Zoology

Ranging behaviour of African wild dog packs in a human‐dominated landscape

Abstract: Movement behaviour is a key component of species' vulnerability to extinction. African wild dogs' Lycaon pictus endangerment has been linked to their wide-ranging behaviour, which is hypothesized to expose them to anthropogenic threats in fragmented habitats. I therefore investigated wild dog movement patterns in an area of Kenya where livestock out-number wild ungulates. In the 9 years of the study, wild dog population density increased from 0.9 to 3.4 adults and yearlings per 100 km2. Home-range size remained unchanged over this time, but overlap between neighbouring home ranges increased. Nevertheless, packs avoided one another and showed evidence of territoriality. Home ranges were of similar size on commercial ranches and community lands, even though people and livestock were abundant, and competitors and large prey depleted, in the latter land use. Packs showed significant habitat preference; in particular, low human densities on commercial ranches, and zoning of settlement on community lands, facilitated wild dog avoidance of human activities and livestock. These findings suggest that, under the right circumstances, wild dogs may be able to avoid anthropogenic threats and thrive in human-dominated landscapes. However, elsewhere in Kenya traditional livestock husbandry is being abandoned and community land is being subdivided. Such changes would greatly reduce wild dogs' ability to survive in pastoral areas.

Chemical stimuli and species recognition in Liolaemus lizards

Abstract: Species-specific recognition systems are fundamental to maintaining the cohesion of species, particularly when heterospecific matings are possible. Here, I examined whether species recognition may facilitate species isolation of Liolaemus lizards, for which up to seven closely related species with similar morphology and ecology may live in sympatry. I also tested whether coexistence with closely related species modulates species recognition. In three Liolaemus species that differ in their current need for species recognition, I investigated their abilities to discriminate chemical stimuli from conspecifics and closely related congeners. For two of these focal species, tests included sympatric and allopatric congeners. The third species, which lives without congeners, was only tested with an allopatric congener. All three species chemo-discriminated between conspecifics and congeners, responding more vigorously to scents produced by their own species. Thus, chemical stimuli may help to maintain reproductive isolation. The existence of species recognition in the allopatric species may be an ancestral trait or may have evolved as a side effect of a within-species recognition system.

Climate variability affects the impact of parasitic flies on Argentinean forest birds

Abstract: The genus Philornis (Diptera: Muscidae) comprises Neotropical parasitic flies that parasitize bird nestlings while in their larval stage. The ecology of most species of these parasitic flies is largely unknown. Here, we contribute with data that shed some light on the environmental factors that are associated with variations in parasitism intensity of Philornis torquans, and examine whether increased intensity is followed by greater probability of mortality or reduced nestling growth. Intensive examination of nestlings of the bird community present in a 30 ha area was carried out weekly along two breeding seasons in Santa Fe, Argentina. Some nestlings of the most frequently parasitized bird species were followed twice a week, from hatching to fledging, to assess the impact of the parasites. High average maximum temperature and increased rainfall were significantly positively correlated with mean Philornis intensity. In turn, heavily parasitized nestlings were more likely to die: 10 larvae doubled the chances of mortality, and growth was affected in those that survived. The greater precipitation and warmer weather predicted for some areas of South America pose a potential impact on nestlings via this parasitism, and consequently on the population dynamics of native birds.

Who are you looking at? Hadeda ibises use direction of gaze, head orientation and approach speed in their risk assessment of a potential predator

Abstract: Animals may update their assessment of predation risk according to how a potential predator approaches them. For example, the predator's head and gaze orientation (direction of attention) may reveal its intentions, and faster-approaching predators are likely to represent greater risk. We examined the reactions of hadeda ibises Bostrychia hagedash. These large birds demonstrate a wide repertoire of responses to being approached (e.g. continuing to forage, slow walking, rapid escape walking, flight and alarm calling). Birds were approached tangentially 112 times by a human who either had the head and eyes directed towards (65 approaches) or directed away from (47 approaches) the birds to test the hypothesis that the direction of the observer's attention informs alert distance (AD) and flight initiation distance (FID) in these birds. Direction of attention had a significant effect on AD and FID as well as the likelihood of taking flight and alarm calling by hadedas, with birds appearing to associate attention directed towards them as an indication of increased risk. Hadedas were able to differentiate between the direction of attention of an approaching human, whether or not there were multiple other humans in the near vicinity. We also examined whether the observer's approach speed altered the birds' responses. Approach speed affected the birds' FID, suggesting that they perceive greater danger in a faster-approaching intruder compared with a slower-walking one. These results support the predictions of optimal escape theory and emphasize the high resolution of anti-predatory awareness in these birds. The marked success of hadeda ibises in urban environments may be due to their ability to become habituated to human presence and to modify their antipredator behaviour in response to subtle cues. These may be common traits of bird species that successfully adapt to urban environments.

Description of a new octoploid frog species (Anura: Pipidae: Xenopus) from the Democratic Republic of the Congo, with a discussion of the biogeography of African clawed frogs in the Albertine Rift

Abstract: We describe a new octoploid species of African clawed frog (Xenopus) from the Lendu Plateau in the northern Albertine Rift of eastern Democratic Republic of the Congo. This species is the sister taxon of Xenopus vestitus (another octoploid), but is distinguished by a unique morphology, vocalization and molecular divergence in mitochondrial and autosomal DNA. Using a comprehensive genetic sample, we provide new information on the species ranges and intra-specific diversity of African clawed frogs from the Albertine Rift, including the details of a small range extension for the critically endangered Xenopus itombwensis and previously uncharacterized variation in Xenopus laevis. We also detail a new method for generating cytogenetic preparations in the field that can be stored at room temperature for up to 3 weeks. While extending our understanding of the extant diversity in the Albertine Rift, this new species highlights components of species diversity in ancestral African clawed frogs that are not represented by known extant descendants.

Telomere dynamics in relation to early growth conditions in the wild in the lesser black-backed gull

Abstract: There has recently been much interest in the long-term effects of early growth conditions. Telomeres, the repetitive DNA sequences that cap eukaryotic chromosomes, are potentially a useful tool for studying such effects. Telomeres shorten at each cell division and considerable evidence links the rate at which they do so with cellular and organismal senescence. Previous research has shown that telomere loss is greatest during early life, so conditions during this time could significantly affect telomere attrition, and in this way, possibly also senescence rates. However, relatively little is known about the pattern of telomere loss under natural conditions. We examined telomere dynamics during growth under natural conditions in the lesser black-backed gull Larus fuscus. Although telomere length significantly decreased with age during the chick period, there was a considerable amount of inter-individual variation in both absolute telomere length and the rate of telomere shortening. While no one factor explained a significant amount of this variation, the trends in the data suggested that circumstances during embryonic growth were linked to hatching telomere length. There was a trend for larger hatchlings to have shorter telomere lengths [effect size=-0.18 +/- 0.11 kb, 95% confidence interval (CI): -0.40, 0.05], suggesting that embryonic growth rate could have affected telomere attrition. Independent of this trend, males tended to have longer telomeres at hatching than females (effect size=0.77 +/- 0.40 kb, 95% CI: 1.55, -0.02). Egg volume and laying date had no relation to telomere length. There was a strong relationship between telomere length at hatching and at 10 days old (effect size=0.52 +/- 0.22, 95% CI: 0.94, 0.09), demonstrating that the variation in hatching telomere length caused by embryonic growth conditions remained consistent during the initial post-hatching period.

The expansion of the house mouse into north-western Europe

Abstract: The western house mouse Mus musculus domesticus is a human commensal, and as such, its phylogeography relates to historical human settlement patterns and movements. We investigate the phylogeography of house mice in northern France and the British Isles (particularly Ireland and the Scottish islands) using microsatellite data and mitochondrial (mt) control region sequences from modern and museum material, placing these in a Europe-wide context. The majority of mtDNA sequences from northern France belong to a clade widespread across the British mainland and Germany, supporting an earlier suggestion that this clade distribution represents colonization by house mice in the Iron Age. The presence of the clade in south-western Ireland indicates possible Iron Age colonization there as well. However, the majority of the Irish sequences belong to a clade elsewhere associated with Norwegian Viking activity, and likely represent the main wave of house mouse colonization of Ireland, arriving from the Scottish islands during the Viking period and linked to urbanization. The St Kilda sequences (from 100-year-old museum samples of the extinct form ‘Mus muralis’ of Barrett-Hamilton) and sequences from South Uist and Lewis also belong to this clade. The clustering of populations shown by the microsatellite data is distinctly different from the mtDNA phylogeny, with populations grouping by geographic proximity, possibly reflecting the genetic effects of secondary colonization. When the mtDNA sequence data are placed in a Europe-wide context, it is clear that the distributions of the two prevalent clades from the vicinity of the British Isles are essentially limited to north-western Europe. These two clades show no evidence of expansion through central Europe, and may therefore reflect maritime colonization.

Seasonal changes in sexual size dimorphism in northern chamois

Abstract: In many polygynous mammals, sexual size dimorphism (SSD) is thought to have evolved through sexual selection, because larger males prevail in male–male combat and secure access to estrous females. SSD is often correlated with higher age-specific mortality of males than of females, possibly because males have higher nutritional requirements and riskier growth and reproductive tactics. In adult chamois Rupicapra rupicapra, sexual dimorphism in skeletal size was about 5%, but dimorphism in body mass was highly seasonal. Males were about 40% heavier than females in autumn but only 4% heavier in spring. For a given skeletal size, males were heavier than females only in autumn. Chamois sexual dimorphism appears mainly due to greater summer accumulation of fat and muscle mass by males than by females. Male mass declines rapidly during the rut. Limited dimorphism in skeletal size combined with substantial but seasonal dimorphism in mass has not been reported in other sexually dimorphic ungulates. Seasonal changes in mass allow males to achieve large size for the rut by accumulating body resources during summer. The use of these resources over the rut may reduce mortality associated with sustaining a large size over the winter.

Does land use affect perceptual range? Evidence from two marsupials of the Atlantic Forest

Abstract: Perceptual range is one of the main determinants of dispersal success in fragmented landscapes, which are composed of scattered remnants of original habitat in a matrix of variable composition. How perceptual range varies according to land use is essential information to estimate the functional connectivity of landscapes. We determined for the first time how different types of land use affect the perceptual range of a species, using as model organisms two neotropical marsupials endemic to the Atlantic Forest in Brazil (Philander frenatus and Didelphis aurita). We released and tracked the movements of 196 individuals in three types of land use commonly found in fragmented landscapes: manioc plantation, mowed pasture and abandoned pasture. We also determined how orientation to the nearest forest fragment is affected by distance to the fragment, wind speed, body mass and sex using a model selection approach. The type of land use affected the perceptual ranges of both marsupials. The estimated perceptual ranges for P. frenatus and D. aurita were 100 and 200 m in the mowed pasture, respectively, 50 and <30 m in the abandoned pasture and 30 and 50 m in the plantation. The orientation of both species decreased with increasing distance to the fragment, but for D. aurita orientation also increased with the wind speed and body mass. These results agree with previous studies depicting a general pattern of increased perceptual range with lower vegetation obstruction in the matrix and larger body mass and wind speed, depending on the use of visual versus olfactory cues by animals. Our findings allow more realistic estimates of functional connectivity in fragmented landscapes based on basic information on the biology of each species and the type of matrix.

Contrasted thermal preferences translate into divergences in habitat use and realized performance in two sympatric snakes

Abstract: Temperature influences ectotherm fitness by affecting physiological performance. Terrestrial reptiles behaviourally regulate their body temperature by selecting particular microhabitats or activity periods. In temperate climates, thermal constraints make precise thermoregulation costly. Theoretical models of thermoregulation predict that species in cool environments should exhibit lower optimal temperature for performance and lower thermal preferences to minimize thermoregulatory costs. Empirical data in support of this prediction remain equivocal because several species maintain high and constant body temperatures, even in cool environments. We studied two largely sympatric colubrid snakes, Hierophis viridiflavus and Zamenis longissimus that share numerous morphological and ecological similarities, but differ markedly in thermal preference. Our objective was to quantify their thermoregulatory strategies in the field to determine how thermal preferences translate in habitat use and performance gain. The thermophilic species, H. viridiflavus, selected open microhabitats, whereas Z. longissimus, which prefers cooler temperatures, used a greater diversity of microhabitats. The two species differed markedly in their exposure levels. Hierophis viridiflavus was constrained to shuttle between sun and shade to maintain preferred body temperatures rendering it very exposed, while covered microhabitats were usually thermally compatible with the requirements of Z. longissimus. High exposure was apparently counterbalanced by higher locomotor performances in H. viridiflavus. The divergence in thermal ecology between Z. longissimus and H. viridiflavus likely reflects different trade-offs between energy gain and predator avoidance.

Effects of habitat fragmentation on population structure and long‐distance gene flow in an endangered marsupial: the woylie

Abstract: A deep understanding of population structures and of the relationships among populations is fundamental to guarantee adequate management of endangered species. We used a molecular approach (12 microsatellite loci and mitochondrial DNA) to investigate these aspects in the woylie or brush-tailed bettong Bettongia penicillata ogilbyi. Four distinct indigenous populations were identified in this study (i.e. Dryandra woodland and Tutanning nature reserve in the wheatbelt region and two discrete populations in the Upper Warren in the south-west forests of Western Australia). Additionally, previously undisclosed modern and historical connections between these units became evident, such as the historical connection between populations at 150 km distance (Dryandra and Upper Warren) and the contemporary gene flow between the two populations in Upper Warren (up to 60 km). Genetic attributes of the four populations were analysed and the evidence of unique genetic material in each of these populations indicated that conservation effort should aim towards the preservation of all these units. Additionally, the lower genetic diversity of the woylie population in Tutanning nature reserve prompted the need for the investigation of factors that are limiting the demographic growth of this population. This study enhances not only our knowledge about the ecology of woylies but also the genetic consequences of habitat fragmentation and reiterates the strength and pertinence of molecular techniques in similar investigations.

Phylogeography and cryptic diversity of the solitary-dwelling silvery mole-rat, genus Heliophobius (family: Bathyergidae)

Abstract: SYNTHESYS grant (BE-TAF-289), grants from the National Research Foundation, the University of Pretoria South Africa (to NCB) and the ERANDA and Bay Foundations (FC).

The definition of sexual selection and its implications for dinosaurian biology

Abstract: We are delighted by the constructive and thoughtful comments of Knell & Sampson (2010) on our original article (Padian H whereas, to Knell and Sampson, sexual selection does not require sexual dimorphism, and mate recognition is a more closely related concept to sexual selection. In our view, Charles Darwin understood organismal biology better than anyone of his time, partly because he thought through problems so thoroughly. In devising his theory of natural selection, he realized that certain living animals bore some salient phenotypic characteristics, such as horns and antlers, that could not be readily explained through the agency of natural selection. He knew that these sorts of features (and their associated behaviors) would pose a threat to the acceptance of his theory of natural selection (because they would be seen as fatal exceptions), and he also understood that these features were not, in most cases, directly relevant to an individual’s survival (i.e. ecologically adaptive). Rather, they helped an individual attract mates or repel rivals for mates. The opposite sex lacked these features (or did not use them in mating). To this phenomenon he gave the name sexual selection, and he explicitly defined it (1859, pp. 89–90 and nearly the same words in 1871, p. 243) by stating that these features were present in one sex and not the other, and that they either attracted mates or repelled rivals. This was the genesis of the term sexual selection. Darwin needed this concept as a contrast to natural selection, in order to defuse a false argument of his detractors; he knew exactly what he was doing. Darwin cannot be ‘wrong’ about the definition of this concept, despite the protests or confusion of later authors, because he invented it, and his empirical basis for it is entirely valid; he was not ‘imprecise’ (pace Carranza, 2009). Myriad examples prove the presence of distinct, monosexual characters in species that are used to attract mates and repel rivals (Darwin, 1871; Andersson, 1994). Thus, the only possible definition of sexual selection requires sexual dimorphism (and not simply allometric sexual differences: Padian & Horner, 2010). To say this does not deny that many factors are involved in the attraction of mates, the repulsion of rivals, success in mating and the differential production of offspring. But sexual selection is only a small part of this, and Darwin was not trying to explain all aspects of mate recognition, attraction, competition and reproductive success. The notion that sexual selection involves more or different aspects than those defined by Darwin is an historical error of misinterpretation in the scholarly literature that has sadly become entrenched. But one cannot change the definition of a term at will. This only creates confusion and fosters misinterpretation [consider the later misuses of Van Valen’s (1973) original concept of the ‘Red Queen,’ which denoted the control of energy in an ecosystem by individual species]. We acknowledge that Darwin’s term is widely misused in the recent literature, and unfortunately, this has brought confusion to an extremely interesting and productive field. Futuyma (2009), whose textbooks have been the ne plus ultra of the field for many years, views sexual selection as a subtype of natural selection, and many biologists agree. There is an historical context for this misunderstanding. In the early 20th century, mathematical modelers of the Modern Synthesis needed to examine whether natural selection could be a viable force in populations (Mayr & Provine, Journal of Zoology

Genetic diversity in birds is associated with body mass and habitat type

Abstract: In some organisms, their habitat can broadly predict their population genetic diversity. For example, marine fishes harbor considerably more genetic diversity than do freshwater fishes because of the larger long-term evolutionary effective population sizes in the former. Body mass (BM) is another predictor of genetic variation, in that small-bodied mammals generally have higher rates of molecular evolution than large mammals. Does genetic variation in birds vary similarly? We investigated the relationships among microsatellite DNA diversity, BM and habitat type (aquatic or terrestrial) in 76 avian species. Our results show that across 1008 avian microsatellite loci, mean heterozygosity was positively correlated with the number of alleles per species. The mean level of heterozygosity and allele number in birds were similar to those of mammals and reptiles, but smaller than fishes. Terrestrial birds have greater genetic diversity (both in terms of mean heterozygosity and allelic diversity per population) than aquatic species. BM of aquatic birds was significantly larger than that of terrestrial birds and there was a negative relationship between mean heterozygosity and BM. Our results, interpreted in light of previously published data from other vertebrates, suggest that patterns of genetic diversity in birds depends on their evolutionary effective population size (determined in part by ecological and environmental features) and on the rate of molecular evolution.

Diet, morphology and performance in two chameleon morphs : do harder bites equate with harder prey?

Abstract: Ecologically induced morphological variation has been identified as a mainstay in evolutionary theory. Species that inhabit different habitats are likely to display morphological and functional differences related to the exploitation of different dietary resources available in each habitat within limits imposed by trade-offs. Here, we examine two populations of the Cape Dwarf Chameleon, Bradypodion pumilum, from fynbos (heathland) and woodland to investigate whether head morphology and bite performance are related to diet within and between populations. Stomach contents are compared with prey availability to test whether chameleons are selective with respect to prey size, hardness and evasiveness. Our data show that for adult chameleons from the fynbos (Kogelberg; n = 44), mean and maximum prey size are tightly correlated with head morphology and performance. In woodland habitat (Stellenbosch; n = 52), only maximum prey size is correlated with head morphology and performance. Fynbos chameleons showed no preference with respect to prey hardness, while those from woodland ate less hard and/or sedentary prey than available, thus preferring items that were soft and/or evasive. Finally, fynbos chameleons have a diet of sedentary and/or evasive prey similar in proportions to that available. Our results suggest that diet is not directly related to selection on the head morphology and biting performance of B. pumilum in woodland habitat, but that it may be important for selection in fynbos due to a reduction in overall prey availability.

Individual differences in the behavioural responses of meadow voles to an unfamiliar environment are not correlated with variation in resting metabolic rate

Abstract: Resting metabolic rate (RMR) is highly variable between individuals within a single species and the relationship between body mass and RMR does not wholly explain this variability. One factor that could account for a portion of the residual variation is animal personality or consistent individual differences (CIDs) in behaviour, but no study has examined this relationship in a free-living population of mammals. In this paper, we test for a relationship between RMR and CIDs in activity in live-trapped meadow voles Microtus pennsylvanicus after controlling for the effect of body mass. We quantified the activity levels of voles both in an unfamiliar environment and for the first 2 min in the metabolic apparatus, and then measured RMR using open-flow respirometry. As expected, there was a linear relationship between RMR and body mass, and we found strong evidence for repeatable differences in activity levels between individuals. However, contrary to the hypothesis, we did not identify a significant correlation between CIDs in behaviour and RMR after controlling for body mass. Our results suggest that, at least within species, higher activity levels may not require a greater investment in energetically demanding tissues or increased capacity for processing of energy. Alternatively, if a relationship exists, our inability to detect it may reflect a weak behavioural signal in noisy RMR data that are influenced by many factors. Our results could also reflect an artefact of individual responses to stress or a sampling bias towards more exploratory individuals in animals captured by live-trapping.

Population density of Geoffroy's cat in scrublands of central Argentina

Abstract: We studied the density of a Geoffroy's cat Leopardus geoffroyi population in a semiarid scrubland of Argentina, by comparing density estimates obtained during camera-trapping surveys in a national park and in nearby cattle ranches in 2006 and 2007–2008. Overall, we obtained 247 pictures of Geoffroy's cats. The density (mean ±se) of the species at the park ranged from 1.2 ± 0.3 to 2.9 ± 1.4 individuals km−2, depending on the buffer applied, whereas density estimates at ranches were on average 32% lower. Only 11% of the Geoffroy's cats identified in 2006 could still be detected in the area 2 years later, indicating that there was a high turnover of individuals in this population. The sex ratio (M:F) estimated during both surveys at the park was 1:1.4, whereas at the ranches it was 1:0.8. The capture success of sympatric pampas cats Leopardus colocolo and jaguarundis Puma yagouaroundi was <0.3 records per 100 trap-days, and no evidence of these species was found in the ranches. Geoffroy's cats seem to be tolerant to some degree of habitat alteration produced by livestock management, and the numerical response of this species in ranches could be largely the result of human persecution and the effects of livestock management on the habitat structure and prey base.

Speckles of cryptic black‐headed gull eggs show no mechanical or conductance structural function

Abstract: The structural-function hypothesis provides an alternative to signalling-based predictions to explain the remarkable diversity observed in avian eggshell colour. According to the hypothesis, protoporphyrin, the common pigment of visible speckles, lubricates and thus strengthens the shell and simultaneously moderates gas transfer across it. Correlational evidence for the structural-function hypothesis in form of a coincidence of both shell thinning and reduced evaporation with eggshell speckles comes from a restricted set of species with limited calcium supply or little nest predation and no need for camouflage of the eggs. Here, we investigate whether protoporphyrin-based pigmentation similarly affects a species with cryptically marked eggs and ample dietary calcium, the black-headed gull, Larus ridibundus. Although shell thinning of speckles occurred, this effect was minimal compared with thinning through embryonic growth. Furthermore, speckled and plain areas of the shell did not differ in water vapour conductance through the shell. We conclude that protoporphyrin speckling does not fulfil a structural function in gull eggs. Instead, during shell formation where the protoporphyrin of speckles is deposited in place of calcite it could inflict a structural cost. We propose that the mechanical and water vapour conductance functions of shell speckling need to be evaluated as separate hypotheses and that both functions could, in fact, negatively affect each other.