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

Plasma progesterone concentrations measured by radioimmunoassay in the Natal clinging bat remained below 2.01 ng/ml during lactational anoestrus but increased significantly during the period of delayed implantation. Values peaked at implantation but were followed by a significant decrease thereafter. Concentrations remained low (less than 6.0 ng/ml) during the initial period of fetal development (153-180 days post coitum) and attained peak values (85.6-181.3 ng/ml) 216-222 days after fertilization. The marked post-implantation increase in progesterone concentrations coincided with a significant increase in placental weight.

/pdf/plasma-progesterone-concentrations-in-the-female-natal-huq4mtu0ly.pdf

Plasma progesterone concentrations in the female Natal clinging bat (Miniopterus schreibersii natalensis).

Elephant numbers in Kafue National Park, Zambia

Coastal Dune Forest Rehabilitation: A Case Study on Rodent and Bird Assemblages in Northern Kwazulu-Natal, South Africa

Circulating concentrations of progesterone, progesterone-binding plasma proteins (PBPP) and oestradiol-17 beta in pregnant porcupines remained relatively low until Days 25-30 post coitum. Progesterone values peaked (102-180 ng/ml; N = 3) 42-60 days post coitum and the rapid increase in oestradiol-17 beta concentrations approximated that of progesterone with peak values (170-210 pg/ml) being attained 60-85 days post coitum. The pattern of PBPP synthesis, as suggested by circulating concentrations, was closely related to that of plasma progesterone, with values remaining low (less than 20 pmol/ml) until Day 31 post coitum, reaching peak levels at Days 50-56 and Days 73-77 post coitum. The production of PBPP during pregnancy is, as in related New World hystricomorph species, considered to be a mechanism which facilitates a reduction in the rate of progesterone metabolism during pregnancy.

/pdf/circulating-progesterone-progesterone-binding-proteins-and-3m0pcnls7w.pdf

Circulating progesterone, progesterone-binding proteins and oestradiol-17β concentrations in the pregnant Cape porcupine, Hystrix africaeaustralis

The modulatory effects of gestational age and circulating concentrations of progesterone, 5-pregnane-3,20-dione, and estradiol-17 on the uterine sex steroid hormone receptor levels of the African elephant were investigated. Uterine tissue biopsies and blood samples were obtained from animals culled in the Kruger National Park. Estrogen and progesterone receptor concentrations were determined in uterine biopsies from subadult, lactating, early-, mid-, and late-pregnant elephants, by equilibrium binding assays. Circulating estradiol-171 and progesterone concentrations were measured by means of RIAs, while plasma concentrations of 5-pregnane-3,20-dione were determined with an amplified ELISA. Significant inverse correlations of the concentrations of estrogen and progesterone receptors with the gestational stage of the elephants were observed. Pregnant uterine horns of individual animals contained lower levels of estrogen and progesterone receptors than the nonpregnant horns of the same animals. A strong positive correlation existed between uterine estrogen and progesterone receptors levels. Circulating concentrations of 5a-pregnane-3,20dione and progesterone decreased with an increase in the concentrations of progesterone receptors as well as with fetal age. We conclude that the progesterone receptor concentrations are down-regulated with progressing gestation in the African elephant. This down-regulation appears to be linked to an increase in circulatory 5-pregnane-3,20-dione concentration in the

R. J. van Aarde

Papers

Plasma progesterone concentrations in the female Natal clinging bat (Miniopterus schreibersii natalensis).

Elephant numbers in Kafue National Park, Zambia

Coastal Dune Forest Rehabilitation: A Case Study on Rodent and Bird Assemblages in Northern Kwazulu-Natal, South Africa

Circulating progesterone, progesterone-binding proteins and oestradiol-17β concentrations in the pregnant Cape porcupine, Hystrix africaeaustralis

Influence of gestation on uterine endometrial steroid receptor concentrations in the African elephant, Loxodonta africana.