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

Movement of individual organisms is fundamental to life, quilting our planet in a rich tapestry of phenomena with diverse implications for ecosystems and humans. Movement research is both plentiful and insightful, and recent methodological advances facilitate obtaining a detailed view of individual movement. Yet, we lack a general unifying paradigm, derived from first principles, which can place movement studies within a common context and advance the development of a mature scientific discipline. This introductory article to the Movement Ecology Special Feature proposes a paradigm that integrates conceptual, theoretical, methodological, and empirical frameworks for studying movement of all organisms, from microbes to trees to elephants. We introduce a conceptual framework depicting the interplay among four basic mechanistic components of organismal movement: the internal state (why move?), motion (how to move?), and navigation (when and where to move?) capacities of the individual and the external factors affecting movement. We demonstrate how the proposed framework aids the study of various taxa and movement types; promotes the formulation of hypotheses about movement; and complements existing biomechanical, cognitive, random, and optimality paradigms of movement. The proposed framework integrates eclectic research on movement into a structured paradigm and aims at providing a basis for hypothesis generation and a vehicle facilitating the understanding of the causes, mechanisms, and spatiotemporal patterns of movement and their role in various ecological and evolutionary processes. "Now we must consider in general the common reason for moving with any movement whatever." (Aristotle, De Motu Animalium, 4th century B.C.).

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A movement ecology paradigm for unifying organismal movement research

Agent-based complex systems are dynamic networks of many interacting agents; examples include ecosystems, financial markets, and cities. The search for general principles underlying the internal organization of such systems often uses bottom-up simulation models such as cellular automata and agent-based models. No general framework for designing, testing, and analyzing bottom-up models has yet been established, but recent advances in ecological modeling have come together in a general strategy we call pattern-oriented modeling. This strategy provides a unifying framework for decoding the internal organization of agent-based complex systems and may lead toward unifying algorithmic theories of the relation between adaptive behavior and system complexity.

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Pattern-oriented modeling of agent-based complex systems: lessons from ecology

Mammalian carnivores are particularly vulnerable to extinction in fragmented landscapes1, and their disappearance may lead to increased numbers of smaller carnivores that are principle predators of birds and other small vertebrates. Such ‘mesopredator release’2 has been implicated in the decline and extinction of prey species2,3,4,5,6. Because experimental manipulation of carnivores is logistically, financially and ethically problematic6,7, however, few studies have evaluated how trophic cascades generated by the decline of dominant predators combine with other fragmentation effects to influence species diversity in terrestrial systems. Although the mesopredator release hypothesis has received only limited critical evaluation8 and remains controversial9, it has become the basis for conservation programmes justifying the protection of carnivores6. Here we describe a study that exploits spatial and temporal variation in the distribution and abundance of an apex predator, the coyote, in a landscape fragmented by development. It appears that the decline and disappearance of the coyote, in conjunction with the effects of habitat fragmentation, affect the distribution and abundance of smaller carnivores and the persistence of their avian prey.

Mesopredator release and avifaunal extinctions in a fragmented system

In response to ever-increasing anthropogenic changes to natural ecosystems, regional, national and international organizations have established guidelines for monitoring biological diversity. Most monitoring programs, however, do not take full advantage of the potential afforded by molecular genetic markers, which can provide information relevant to both ecological and evolutionary time frames, while costing less and being more sensitive and reliable than traditional monitoring approaches. As several molecular and computational approaches are relatively new, many technical and theoretical issues remain to be resolved. Here, we illustrate how DNA and population genetic data can provide valuable information, often unattainable via other approaches, for monitoring species of management, conservation and ecological interest.

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Genetic monitoring as a promising tool for conservation and management

Interspecific killing among mammalian carnivores is common in nature and accounts for up to 68% of known mortalities in some species. Interactions may be symmetrical (both species kill each other) or asymmetrical (one species kills the other), and in some interactions adults of one species kill young but not adults of the other. There is a positive significant relationship between the body masses of solitary killer species and body masses of their victim species, and grouping species kill larger victims than solitary species. Interactions and consumption of the victim appear more common when food is scarce or disputed. In response to killers, victim species may alter their use of space, activity patterns, and form groups. Consequences of interspecific killing include population reduction or even extinction, and reduction and enhancement of prey populations, and may therefore have important implications for conservation and management of carnivores and their prey.

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Interspecific Killing among Mammalian Carnivores

Top predators have often been persecuted because of their supposed negative effects on species of economic concern on which they feed. In some cases, however, they may actually benefit their prey through intraguild predation on other smaller predators that share the prey. In each of two representative situations, in one of which lynx were present and in the other absent, we (1) estimated gross numbers of rabbits taken by lynx and Egyptian mongooses (smaller predators that are themselves preyed upon by lynx); (2) simulated size-structured rabbit populations of different densities, taking into account the reproductive value of the individuals taken by predators; and (3) estimated actual rabbit densities. Numbers of rabbits taken by predators during a year werefound to be between 4.8 and 9.5 times greater when lynx were notpresent. After ayear, rabbit population growth for an initial rabbit density of 15/ha was between 12% and 22% lower when lynx were not present For lower initial rabbit densities, the positive effect of lynx presence on rabbits was greater. Actual rabbit densities in the areas used by lynx were 2-4 times higher than in areas not used by lynx, even though these areas were similar or identical in habitat composition. These results support the suggestion that removal of top predators may sometimes have a negative effect on prey populations of human economic concern.

Positive Effects on Game Species of Top Predators by Controlling Smaller Predator Populations: An Example with Lynx, Mongooses, and Rabbits

Noninvasive methods using genetic markers have been suggested as ways to overcome difficulties associated with documenting the presence of elusive species. We present and assess a novel, reliable and effective molecular genetic technique for the unequivocal genetic identification of faeces from the endangered Iberian lynx ( Lynx pardinus ). From mitochondrial DNA (mtDNA) cytochrome b and D -loop region sequences, we designed four species-specific primers (for products 130–161 bp long) that were considered to be likely to amplify degraded DNA. We compared two DNA extraction methods, various DNA amplification conditions and the robustness and specificity of the primer pairs with 87 lynx samples from 5 potentially different lynx populations and with 328 samples of other carnivore species. The utility of the identification technique was tested with faeces of different ages, with faeces from controlled field experiments, and with faeces collected from locales with possible lynx populations from throughout the state of Andalusia, Spain (8052 km 2 ). Faecal mtDNA extraction was more efficient using PBS wash of the faeces instead of a faeces homogenate. Our assay increased from 92.6 to 99% efficiency with a second amplification and a reduction in template concentration to overcome polymerase chain reaction (PCR) inhibition. Our assay never produced false positives, and correctly identified all lynx faeces. Of 252 faeces samples of unknown species collected throughout Andalusia, 26.6% (from three different areas) were classified as Iberian lynx, 1.4% showed evidence of PCR inhibition and 1.2% were of uncertain origin. This method has proven to be a reliable technique that can be incorporated into large-scale surveys of Iberian lynx populations and exemplifies an approach that can easily be extended to other species.

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Faecal genetic analysis to determine the presence and distribution of elusive carnivores: design and feasibility for the Iberian lynx.

Previous studies carried out in the Donana National Park reported that red foxes (Vulpes vulpes) were killed by Iberian lynxes (Lynx pardinus), whereas similar-sized Eurasian badgers (Meles meles) were not. Therefore, we predicted that fox would avoid lynx predation risk by niche segregation whereas we did not expect such a segregation between badger and lynx. As an approach for evaluating our predictions, we compared their diet, activity patterns, and habitat use in an area of Donana where the three carnivores are sympatric. Lynxes preyed almost uniquely on European rabbits (Oryctolagus cuniculus), and though badgers and foxes were omnivorous, rabbits also were a major prey, resulting in high overlaps throughout the year. However, badgers preyed largely on small rabbits, whereas lynxes and foxes preyed mainly on medium-sized rabbits. There were also interspecific differences in activity patterns. Maximum levels of activity among lynxes were during sunrise and dusk (49–67%). Foxes were most active during dusk and night (34–67%), and badgers were mainly nocturnal (53–87%). Though there were seasonal differences in the amount of activity of each species, specific activity patterns changed little throughout the year. There was a strong difference in annual habitat use by the three species (P < 0.0001). Lynxes used mainly the Mediterranean scrubland during both the active (PMAX) and the resting (PMIN) periods. During PMIN, foxes used the Mediterranean scrubland intensively (40% of locations on average), but during PMAX, they used the pastureland much more intensively despite this habitat being poorer in their main prey (rabbits). As a consequence, foxes and lynxes exhibited segregation in their habitat use during the active period. Badgers also used the Mediterranean scrubland intensively, especially during PMIN. There were no seasonal differences in habitat use for lynx and fox, but there was for badgers (P < 0.015). Within the study area, the three species selected habitat suggesting they were sensitive to factors such as vegetation and prey abundance. However, in general, carnivore habitat use did not correlate with rabbit abundance. We propose that foxes avoided lynxes by using, during activity, habitats not frequented by lynxes, and that a low predation risk associated with the distinctive foraging mode of badgers may facilitate its coexistence with other carnivores.

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Niche relations among three sympatric Mediterranean carnivores

Spatial ecology and diet of Iberian lynx (Lynx pardinus) and the abundance of its main prey, the European rabbit (Oryctolagus cuniculus), were studied in southwestern Spain from December 1992 to December 1996 when a decline in rabbit populations occurred. Our objectives were to relate spatial ecology of lynx to rabbit abundance, water availability, and protection from human disturbance. Rabbits were almost the sole prey of lynx; rabbit remains were present in 99.2% (n = 1,171) of feces analyzed. Rabbit abundance and density in 6 different habitats were estimated by line transect sampling. Rabbits were more abundant in Mediterranean scrubland, closely followed by ash stands. Pastureland and lentiscus in plantations had 4.5 times fewer rabbits, and pine plantations 15-20 times fewer rabbits, than the Mediterranean scrubland. Abundance of rabbits in the Mediterranean scrubland was not spatially uniform, as density for 1994 and 1995 varied from 42-55/ha in the area close to the edge of the marsh (locally called the Vera) to 2-7/ha far from the Vera. Rabbit density was 3.5 times higher during spring than during autumn. A decline in rabbit density occurred in 1996 when numbers were 72-91 % lower than the previous years. We mapped warren density in Mediterranean scrubland and pastureland to determine intra-habitat differences in spatial distribution of rabbits. Warren density, entrance density, and mean number of entrances per warren declined significantly with distance from the Vera in the Mediterranean scrubland, following a negative exponential function (adj. r 2 ranging between 83 and 97%). However, none of these variables showed any trend in relation to the Vera in the pastureland. The lynx population contained three stable pairs of adults plus young raised each year, some of which remained on the study area as subadults (older than one year). The seasonal number of different lynx in the study area ranged between 7 and 17. Average adult and young/subadult seasonal density was 0.77 (range = 0.72-0.88) and 0.46 individuals/km 2 (range = 0.07-1.12), respectively. We estimated home range and daily movements of lynx to determine changes that might be due to sex, season, or changing prey density. On average, total lynx home range size was 7.3 km 2 for young, 9.5 km 2 for adult females, and 18.2 km 2 for adult males. Mean core areas (60% isopleth using the kernel approximation) were on average 15%, 10%, and 34% of total home ranges of young, adult females, and adult males, respectively. Significant differences were found for home range and core area sizes among sex-age classes, but neither season nor year affected home range size or core area size. Daily movements averaged 8.0 km. Daily distance traveled was not affected by sex-age class or season, but was different among years, with lynx traveling shorter distances in 1993 and 1996. Daily home range size averaged 1.46 km 2 , and again only varied by year. Lynx daily movements were associated with permanent, artificial water sites. Habitat use by lynx was remarkably constant, with no differences detected among sex-age classes, active or inactive locations, seasons, or years. The habitat most frequently used was Mediterranean scrubland (53% of locations), and both it and ash stands were the only habitats preferred by lynx; pine and eucalyptus plantations were avoided, and marsh, pastureland and lentiscus in plantations were neither preferred or avoided.

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Francisco Palomares

Papers

Interspecific Killing among Mammalian Carnivores

Positive Effects on Game Species of Top Predators by Controlling Smaller Predator Populations: An Example with Lynx, Mongooses, and Rabbits

Faecal genetic analysis to determine the presence and distribution of elusive carnivores: design and feasibility for the Iberian lynx.

Niche relations among three sympatric Mediterranean carnivores

Spatial ecology of Iberian lynx and abundance of European rabbits in southwestern Spain