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

Aim We reviewed the occurrence of Bergmann’s rule in birds (ninety-four species) and mammals (149 species), using only studies where statistical significance of the results was tested. We also tested whether studies using different characters as surrogates of body size have a different tendency to conform to Bergmann’s rule, whether body size and nest type (in birds) have an influence on the tendency to conform to the rule, and whether sedentary birds conform to the rule more than migratory birds. Location Worldwide. Methods We reviewed published data on geographic and temporal variation in body size, using only studies where the statistical significance of the results was tested. We asked how many species conform to the rule out of all species studied in each order and family. Results Over 72% of the birds and 65% of the mammal species follow Bergmann’s rule. An overall tendency to follow the rule occurs also within orders and families. Studies using body mass in mammals show the greatest tendency to adhere to Bergmann’s rule (linear measurements and dental measurements show a weaker tendency); while in birds, studies using body mass and other surrogates (linear measurements and egg size) show a similar tendency. Birds of different body mass categories exhibit a similar tendency to follow Bergmann’s rule, while in mammals the lower body size categories (4–50 and 50– 500 g) show a significantly lower tendency to conform to the rule. Sedentary birds tend to conform to Bergmann’s rule more than migratory species. Nest type does not affect the tendency to conform to Bergmann’s rule. Main conclusions Bergmann’s rule is a valid ecological generalization for birds and mammals.

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On the validity of Bergmann's rule

Quantitative genetic analyses for body size and for life history characters within and among populations of Daphnia obtusa reveal substantial genetic variance at both hierarchical levels for all traits measured. Simultaneous allozymic analysis on the same population samples indicate a moderate degree of differentiation: GST = 0.28. No associations between electrophoretic genotype and phenotypic characters were found, providing support for the null hypothesis that the allozymic variants are effectively neutral. Therefore, GST can be used as the null hypothesis that neutral phenotypic evolution within populations led to the observed differentiation for the quantitative traits, which I call QST. The results of this study provide evidence that natural selection has promoted diversification for body size among populations, and has impeded diversification for relative fitness. Analyses of population differentiation for clutch size, age at reproduction, and growth rate indicate that neutral phenotypic evolution cannot be excluded as the cause.

/pdf/population-structure-in-daphnia-obtusa-quantitative-genetic-29g05zoq4x.pdf

Population structure in Daphnia obtusa: quantitative genetic and allozymic variation.

The ability of populations to undergo adaptive evolution depends on the presence of quantitative genetic variation for ecologically important traits. Although molecular measures are widely used as surrogates for quantitative genetic variation, there is controversy about the strength of the relationship between the two. To resolve this issue, we carried out a meta-analysis based on 71 datasets. The mean correlation between molecular and quantitative measures of genetic variation was weak (r 5 0.217). Furthermore, there was no significant relationship between the two measures for life-history traits ( r 52 0.11) or for the quantitative measure generally considered as the best indicator of adaptive potential, heritability ( r 52 0.08). Consequently, molecular measures of genetic diversity have only a very limited ability to predict quantitative genetic variability. When information about a population's short-term evolutionary potential or estimates of local adaptation and population divergence are required, quantitative genetic variation should be measured directly.

/pdf/how-closely-correlated-are-molecular-and-quantitative-26ltgg70vp.pdf

How closely correlated are molecular and quantitative measures of genetic variation? A meta-analysis

Climate is a driver of biotic systems. It affects individual fitness, population dynamics, distribution and abundance of species, and ecosystem structure and function. Regional variation in climatic regimes creates selective pressures for the evolution of locally adapted physiologies, morphological adaptations (e.g., color patterns, surface textures, body shapes and sizes), and behavioral adaptations (e.g., foraging strategies and breeding systems). In the absence of humans, broad-scale, long-term consequences of climatic warming on wild organisms are generally predictable. Evidence from Pleistocene glaciations indicates that most species responded ecologically by shifting their ranges poleward and upward in elevation, rather than evolutionary through local adaptation (e.g., morphological changes). But these broad patterns tell us little about the relative importance of gradual climatic trends as compared to extreme weather events in shaping these processes. Here, evidence is brought forward that extreme ...

/pdf/impacts-of-extreme-weather-and-climate-on-terrestrial-biota-2efpya0pir.pdf

Impacts of Extreme Weather and Climate on Terrestrial Biota

The bats of Texas

A study of the ecology and distribution of Geomys bursarius jugossicularis Hooper, Thomomys bottae cultellus Kelson, and Pappogeomys castanops Baird was conducted in northeastern New Mexico. Comparisons of body size, soils utilized, burrow characteristics, distinguishing surface features, and winter activity revealed each species to be ecologically separate. Altitude and soils are discussed as factors influencing the geographical separation of the species, although soil appears to be the primary limiting factor. Based on the observed distribution and range of soils inhabited, the most limited distribution and the broadest range of soil types is found for the largest species P. castonops, followed by T. bottae and then G. bursarius.

Ecological Separation of Three Genera of Pocket Gophers (Geomyidae)

Schnell, G. D. (Department of Zoology and Stovall Museum, University of Oklahoma, Norman, Oklahoma 73019), T. L. Best (Natural Sciences Research Institute, Natural History Museum, Eastern New Mexico University, Portales, New Mexico 88130), and M. L. Kennedy (Department of Biology, Memphis State University, Memphis, Tennessee 38152) 1978. Interspecific morphologic variation in kangaroo rats (Dipodomys): degree of concordance with genic variation. Syst. Zool. 27:34-48.-The 24 forms of kangaroo rats (Dipodomys) that have been recognized as species by one or more recent authors were studied using phenetic techniques. A total of 41 morphometric characters (4 skin, 16 skull, and 21 post-cranial) were measured for up to 10 males and 10 females of each species. The standardized average measurements were analyzed and then measurements were divided by principal component I projections based on unstandardized data to reduce the influence of overall size. Phenograms and three-dimensional principal component models were produced and the results compared with the findings of previous authors, including those from allozyme analyses. Several species pairs and groups involving a few species were stable throughout our studies and consistent with groups identified in phylogenetic, specialization, or other classificatory schemes. These include: compactus and ordii; elephantinus and venustus; agilis, paralius, peninsularis, and antiquarius; nitratoides and merriami; and ornatus and phillipsii. However, marked morphologic gaps (other than those based on size) are not present between many of the species groups and attempts to place species into such groups in classifications probably result in an indication of distinctness that goes beyond what is found in nature. In terms of interspecific comparisons, there was no association between phenetic groups based on morphologic data and those constructed using allozyme findings. When comparisons were made among previous classifications and our results, the allozyme data produced the most divergent classifications. Overall, the associations between our morphologic results and previous classifications were relatively weak, reflecting by and large the variance in arrangements of species groups, rather than major differences within groups. Given the relative indistinctness of morphologic groups, it seems unlikely that any one classification can accurately represent interspecific phenetic, cladistic, and/or phylogenetic affinities within the genus. [Phenetics, taxonomic congruence, Dipodomys, kangaroo rats, morphometrics, allozymes.] Significant effort has been expended by a number of investigators studying evolutionary mechanisms to determine the extent of genic variation in local populations, among populations, and among closely related species (see Lewontin, 1974, and Powell, 1975, for general reviews; Selander and Johnson, 1973, summarized data for vertebrates). Workers have attempted to investigate and elucidate a fundamental aspect of evolutionary theory-that race formation and eventually speciation occur by the conversion of genetic variation within populations to variation among populations (Lewontin, 1967). Prakash (1969) emphasized that to understand the speciation process we not only should have a knowledge of genetic differences between closely related species (or populations within a species), but also of the correlation between genic differences and differences based on other characteristics, such as those describing various aspects of morphology, ecological preference, and behavior. Relatively few studies have quantitatively compared interspecific differences in morphology against between species allozyme differences. Sokal (1973) indicated that allozyme variation is an unreliable indicator of classical morphologic (phenetic) variation, citing Sneath and

Interspecific Morphologic Variation in Kangaroo Rats (Dipodomys): Degree of Concordance with Genic Variation

Availability and Ingestion of Lead Shot by Mourning Doves (Zenaida macroura) in Southeastern New Mexico

Measurements of skulls were used to determine if growth continues throughout the lifetime of a puma ( Puma concolor ) and if growth patterns differ between sexes. The dataset included 1,201 adult pumas and consisted of 14 cranial and 5 mandibular measurements. Ages (estimated by the amount of staining and wear of teeth) of specimens examined during our study suggested that few pumas live past ca. 9 years of age in the wild (16 of 609 adult males and 35 of 592 adult females). For both sexes, all of the characters showing no significant variation among age groups were those related to measurements of dentition, indicating that teeth reach their full-grown size by ca. 2 years of age. Growth of the cranium of pumas continues throughout most of the animal's life; males continue to grow to 7–9 years of age, and females continue to grow to 5–6 years of age.

/pdf/age-related-variation-in-skulls-of-the-puma-puma-concolor-23pnvncc5i.pdf

Age-related variation in skulls of the puma (Puma concolor)

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