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

Taking the Berberis aggregate shrubs in the ecotone of dry valley and montane forests in upper reaches of Minjiang River as study objects, and by the methods of tracking grazing and field survey, this paper studied the characteristics of habitat utilization by livestock and the features of grazing-path. The major factors affecting the features of grazing-path were screened by redundancy analysis (RDA), and the relationships of the grazing-path features with the coverage, size class, and distribution pattern of the shrubs were analyzed. It was shown that the distribution pattern of the grazing-path could intuitively reflect the characteristics of the habitat utilization by livestock, being in accordance with the results of tracking grazing. The Morisita index at 5 m scale could objectively reflect the distribution type of the grazing-path. Sample plots 1, 2 and 6 presented a contagious distribution of grazing-path, while the other plots showed regular distribution. In slope scale, the coverage and height of the shrubs were the notable affecting factors, which had negative correlations with the grazing-path features. There was a significant negative correlation between the coverage of B. aggregate population and the area of grazing-path. The population structure of B. aggregate had a close correlation with the distribution of grazing-path. The ratio of the long axis to short axis of the shrubs was averagely 1.29, and the shape of the shrubs approached to round. It was considered that the grazing-path landscape and the livestock on the grazing-paths had the function of reconstructing the shape of the shrubs. The directionality of the population pattern of B. aggregate was generally in line with the distribution type of grazing-path, but actually, they were opposite in distribution. The patches of the shrubs were in aggregated or uniform distribution in the areas deviated from the grazing-path.

/pdf/effects-of-feline-panleucopaenia-on-the-population-55lplusir9.pdf

Effects of feline panleucopaenia on the population characteristics of feral cats on Marion Island.

Understanding the population dynamics of savanna elephants depends on estimating population parameters such as the age at first reproduction, calving interval and age-specific survival rates. The generation of these parameters, however, relies on the ability to accurately determine the age of individuals, but a reliable age estimation technique for free-ranging elephants is presently not available. Shoulder heights of elephants were measured in 10 populations in five countries across southern and eastern Africa. Data included shoulder height measurements from two populations where the age of each individual was known (i.e. Addo Elephant National Park, South Africa and Amboseli National Park, Kenya). From the known-age data, Von Bertalanffy growth functions were constructed for both male and female elephants. Savanna elephants were found to attain similar asymptotic shoulder heights in the 10 populations, while individuals in the two known-age populations grew at the same rate. The Von Bertalanffy growth curves allowed for the accurate age estimation of females up to 15 years of age and males up to 36 years of age. The results indicate that shoulder height can serve as an indicator of chronological age for elephants below 15 years of age for females and 36 years of age for males. Ages derived from these growth curves can then be used to generate age-specific population variables, which will help assess the demographic status of savanna elephant populations across Africa.

Growth and age determination of African savanna elephants

The dental pathology of feral cats on Marion Island, Part II: periodontitis, external odontoclastic resorption lesions and mandibular thickening.

Elephant population biology and ecology

Photogrammetry can be used to measure the body dimensions of a variety of mammals. We 
developed a digital photogrammetry technique and used an infrared laser rangefinder to 
measure the shoulder heights of African elephants ( Loxodonta africana ). Measures of the 
height of objects of known size using digital photogrammetry were between 0.7% shorter to 
0.6% taller than the real values. The rangefinder recorded values that ranged from 0.8% to 
3.6% larger than the real height. When we applied digital photogrammetry to tame elephants, 
measured shoulder heights were 1.6% to 3.4% shorter than those recorded using a custom- 
made calliper. For these elephants, the rangefinder recorded shoulder heights that were 
3.8 to 9.4% smaller than the real values. The digital photogrammetric technique described 
here is less time-consuming and as or more precise than other techniques used to measure 
African elephants.

R. J. van Aarde

Papers

Effects of feline panleucopaenia on the population characteristics of feral cats on Marion Island.

Growth and age determination of African savanna elephants

The dental pathology of feral cats on Marion Island, Part II: periodontitis, external odontoclastic resorption lesions and mandibular thickening.

Elephant population biology and ecology

Digital photogrammetry and laser rangefinder techniques to measure African elephants : research article