Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

The Theory of Island Biogeography

The invasion of ecosystems by exotic species is currently viewed as one of the most important sources of biodiversity loss. The largest part of this loss occurs on islands, where indigenous species have often evolved in the absence of strong competition, herbivory, parasitism or predation. As a result, introduced species thrive in those optimal insular ecosystems affecting their plant food, competitors or animal prey. As islands are characterised by a high rate of endemism, the impacted populations often correspond to local subspecies or even unique species. One of the most important taxa concerning biological invasions on islands is mammals. A small number of mammal species is responsible for most of the damage to invaded insular ecosystems: rats, cats, goats, rabbits, pigs and a few others. The effect of alien invasive species may be simple or very complex, especially since a large array of invasive species, mammals and others, can be present simultaneously and interact among themselves as well as with the indigenous species. In most cases, introduced species generally have a strong impact and they often are responsible for the impoverishment of the local flora and fauna. The best response to these effects is almost always to control the alien population, either by regularly reducing their numbers, or better still, by eradicating the population as a whole from the island. Several types of methods are currently used: physical (trapping, shooting), chemical (poisoning) and biological (e.g. directed use of diseases). Each has its own set of advantages and disadvantages, depending on the mammal species targeted. The best strategy is almost always to combine several methods. Whatever the strategy used, its long-term success is critically dependent on solid support from several different areas, including financial support, staff commitment, and public support, to name only a few. In many cases, the elimination of the alien invasive species is followed by a rapid and often spectacular recovery of the impacted local populations. However, in other cases, the removal of the alien is not sufficient for the damaged ecosystem to revert to its former state, and complementary actions, such as species re-introduction, are required. A third situation may be widespread: the sudden removal of the alien species may generate a further disequilibrium, resulting in further or greater damage to the ecosystem. Given the numerous and complex population interactions among island species, it is difficult to predict the outcome of the removal of key species, such as a top predator. This justifies careful pre-control study and preparation prior to initiating the eradication of an alien species, in order to avoid an ecological catastrophe. In addition, long-term monitoring of the post-eradication ecosystem is crucial to assess success and prevent reinvasion.

http://max2.ese.u-psud.fr/epc/conservation/PDFs/BiolReviews.pdf

Mammal invaders on islands: impact, control and control impact

Island populations are much more prone to extinction than mainland populations. The reasons for this remain controversial. If inbreeding and loss of genetic variation are involved, then genetic variation must be lower on average in island than mainland populations. Published data on levels of genetic variation for allozymes, nuclear DNA markers, mitochondrial DNA, inversions and quantitative characters in island and mainland populations were analysed. A large and highly significant majority of island populations have less allozyme genetic variation than their mainland counterparts (165 of 202 comparisons), the average reduction being 29 per cent. The magnitude of differences was related to dispersal ability. There were related differences for all the other measures. Island endemic species showed lower genetic variation than related mainland species in 34 of 38 cases. The proportionate reduction in genetic variation was significantly greater in island endemic than in nonendemic island populations in mammals and birds, but not in insects. Genetic factors cannot be discounted as a cause of higher extinction rates of island than mainland populations.

/pdf/do-island-populations-have-less-genetic-variation-than-17siuwjycj.pdf

Do island populations have less genetic variation than mainland populations

The evolutionary significance of genetic diversity of proteins in nature remains controversial despite the numerous protein studies conducted electrophoretically during the last two decades. Ironically, the discovery of extensive protein polymorphisms in nature (reviewed by Lewontin, 1974; Powell, 1975; Selander, 1976; Nevo 1978, 1983b; Hamrick et al., 1979; Nelson and Hedgecock, 1980), did not resolve the disagreement between the die ho torn ou s explanatory models of selection (e.g., Ayala, 1977; Milkman, 1978; Clarke, 1979; Wills, 1981) versus neutrality (Kimura, 1968; Kimura and Chta, 1971; Nei, 1975; and modifications in Kimura, 1979atb). The more general problem of the relative importance of the evolutionary forces interacting in genetic population differentiation at the molecular levels of proteins and DNA, i.e., mutation, migration, natural selection and genetic drift, remains now as enigmatic as ever.

The Evolutionary Significance of Genetic Diversity: Ecological, Demographic and Life History Correlates

Natural disturbances such as lava flows, landslides and glacial moraines, and human-damaged sites such as pavement, road edges and mine wastes often leave little or no soil or biological legacy. This 2003 book provided the first comprehensive summary of how plant, animal and microbial communities develop under the harsh conditions following such dramatic disturbances. The authors examine the basic principles that determine ecosystem development and apply the general rules to the urgent practical need for promoting the reclamation of damaged lands. Written for ecologists concerned with disturbance, landscape dynamics, restoration, life histories, invasions, modeling, soil formation and community or population dynamics, this book will also serve as an authoritative text for graduate students and a valuable reference for professionals involved in land management.

/pdf/primary-succession-and-ecosystem-rehabilitation-46xfnlnrj7.pdf

Primary Succession and Ecosystem Rehabilitation

A single intra-muscular injection of a mixture of fentanyl citrate and xylazine hydrochloride or ketamine hydrochloride and xylazine hydrochloride at indicated mean dose rates was effective for the immobilization of porcupines (12 - 18 kg). Handling and immobilization at intervals of two to seven days over extended periods did not impair reproductive activities.

Husbandry and immobilization of captive porcupines Hystrix africaeaustralis

THE DOMESTIC CAT, Felius catus, is polymorphic for a number of coat color, texture, and pattern characteristics that can be recognized with relative ease. The inheritance of these traits is well known and has recently been reviewed. With the exception of a note by Dreux and some remarks on the coat color of cats at Cochons Island, no published information is yet available on the population genetics of the cats inhabiting several sub-Antarctic Islands. A study of the population genetics of the Marion Island cats is of interest for several reasons. The population originated from a limited stock of which the phenotypical constitution is known. It has existed in isolation from other felids (therefore no interbreeding) under extreme environmental conditions. The lack of potential competitors also may have afforded opportunities not available to cats in continental areas. Furthermore, human preferences would not have influenced the frequencies of the different phenotypes.

Gene frequencies in feral cats on Marion Island

Summary

The timing and duration of the male rut were monitored in a population of springbok in the Kalahari from 1984. Timing was random and could not be related to any proximate factor; the duration varied from 5 to 23 days. Springbok rams were shot or captured in the hot-wet, cold-dry and hot-dry seasons from 1988 to 1992. Body condition and testicular exocrine and endocrine functions were measured. Territorial and non-territorial rams were treated in the same way. All body measurements were lower for non-territorial than for territorial rams, but only neck girth differed significantly. Captured animals were stimulated with GnRH and plasma testosterone concentrations were measured over 90 min. Overall, non-territorials showed a greater response than territorial rams. The response of territorial rams to GnRH at the beginning of a rut was significantly less than the response 1 week later. Ewes came into oestrus shortly after the beginning of the male rut; in four of the past five years lambing peaked in the hot-wet season. Rams appeared to be physiologically capable of reproductive activity throughout the year, and responded to various stimuli by exhibiting rutting and/or mating behaviour. The possible stimuli are discussed.



Resume

On a surveille l'occurence et la duree du rut des mâles dans une population de springboks du Kalahari depuis 1984. L'occurence semblait se faire au hasard et ne repondre a aucun facteur evident; la duree allait de 5 a 23 jours. On a tue des springboks mâles en saison chaude et humide, froide et seche, et chaude et seche, de 1988 a 1992. On a mesure la condition physique ainsi que les fonctions testiculaires exocrines et endocrines. Les mâles ont tous ete traites de la meme fa¸on, qu'ils soient territoriaux ou non. Toutes les mensurations corporelles etaient plus petites pour les mâles non territoriaux que pour les mâles territoriaux, mais seul le tour de cou differait significativement. On a stimule des animaux captures avec du GnRH et mesure les concentrations de testosterone dans le plasma au bout de 90 minutes. En general, les mâles non territoriaux montraient une reponse plus forte que les mâles territoriaux. La reponse des mâles territoriaux au GnRH administre au debut du rut etait significativement moindre qu'une semaine plus tard. Les femelles entraient en chaleur peu apres le debut du rut des mâles, et pour quatre des cinq dernieres annees, la mise-bas a culmine pendant la saison chaude et humide. Les mâles semblaient physiologiquement capables d'avoir une activite reproductrice tout au long de l'annee et repondaient a differente stimuli en exhibant un comportement de rut ou d'accouplement. On discute des stimuli possibles.

/pdf/morphometries-and-reproduction-in-a-population-of-springbok-128tcdf4mb.pdf

Morphometries and reproduction in a population of springbok Antidorcas marsupialis in the semi-arid southern Kalahari

Ovaries, fetuses and plasma were collected from zebra mares shot in the Etosha National Park in Namibia between 15 and 25 August 1983. Ovarian weight was affected by reproductive status and most of the non-pregnant mares were anoestrous. The number of follicles varied between individuals and only pro-oestrous/oestrous mares had follicles larger than 20 mm in diameter. The largest follicle in pregnant mares was only 9 mm in diameter. Corpora lutea and corpora albicantia were found in non-pregnant as well as pregnant mares: 4 pregnant mares had only corpora albicantia. The presence of secondary corpora lutea could not be confirmed in any of the pregnant mares. Implantation was estimated to occur at around 73 days of gestation, and most mares (84%) had conceived between November and April. Peripheral concentrations of plasma progesterone during pregnancy varied from 0.5 to 2.4 ng/ml.

/pdf/reproduction-in-female-hartmann-s-zebra-equus-zebra-24tu8tc794.pdf

Reproduction in female Hartmann's zebra, Equus zebra hartmannae

Summary

This paper reports on the successful relocation of captive-bred male servals and provides information on activity patterns, dispersal and spatial utilization. Servals maintain themselves without any prior training in hunting. They are predominantly nocturnal and direction of dispersal was determined by habitat preferences, they confine themselves to areas with permanent water and adequate shelter. Core areas of activity coincided with the points of release and home range size varied from 2.1 to 2.7 km2.



Resume

Cet article rend compte du succes de la reimplantation de servals mâles reproduits en captivite et fournit des informations sur les types d'activite, de dispersion et d'occupation spatiale. Les servals survivent sans entrainement prealable a la chasse. Ils sont avant tout nocturnes et le sens de leur dispersion est determine par des preferences d'habitat, se confinant dans des zones a eau permanente et abri suffisant. Les regions centrales de leur activite coincident avec les zones de lâchage et les domaines vitaux varient de 2, l a 2,7 km2.

R. J. van Aarde

Papers

Husbandry and immobilization of captive porcupines Hystrix africaeaustralis

Gene frequencies in feral cats on Marion Island

Morphometries and reproduction in a population of springbok Antidorcas marsupialis in the semi-arid southern Kalahari

Reproduction in female Hartmann's zebra, Equus zebra hartmannae

Pattern of space use by relocated servals Felis serval