I. the origin of species by means of natural selection

https://www.fs.fed.us/rm/pubs_other/rmrs_2006_cushman_s001.pdf

Effects of habitat loss and fragmentation on amphibians: A review and prospectus

Predators and food are the keys to understanding fish shoals; synchronised co-operation defeats predators, and optimal food gathering in shoals reflects a shifting balance between joining, competing in, or leaving the group In the wild, predators may arrive while shoaling fish are feeding, and so vigilance is a crucial behaviour Once detected, predator defence takes precedence over feeding, since an animal’s life is worth more than today’s dinner

Functions of Shoaling Behaviour in Teleosts

Amphibians are frequently characterized as having limited dispersal abilities, strong site fidelity and spatially disjunct breeding habitat. As such, pond-breeding species are often alleged to form metapopulations. Amphibian species worldwide appear to be suffering population level declines caused, at least in part, by the degradation and fragmentation of habitat and the intervening areas between habitat patches. If the simplification of amphibians occupying metapopulations is accurate, then a regionally based conservation strategy, informed by metapopulation theory, is a powerful tool to estimate the isolation and extinction risk of ponds or populations. However, to date no attempt to assess the class-wide generalization of amphibian populations as metapopulations has been made. We reviewed the literature on amphibians as metapopulations (53 journal articles or theses) and amphibian dispersal (166 journal articles or theses for 53 anuran species and 37 salamander species) to evaluate whether the conditions for metapopulation structure had been tested, whether pond isolation was based only on the assumption of limited dispersal, and whether amphibian dispersal was uniformly limited. We found that in the majority of cases (74%) the assumptions of the metapopulation paradigm were not tested. Breeding patch isolation via limited dispersal and/or strong site fidelity was the most frequently implicated or tested metapopulation condition, however we found strong evidence that amphibian dispersal is not as uniformly limited as is often thought. The frequency distribution of maximum movements for anurans and salamanders was well described by an inverse power law. This relationship predicts that distances beneath 11–13 and 8–9 km, respectively, are in a range that they may receive one emigrating individual. Populations isolated by distances approaching this range are perhaps more likely to exhibit metapopulation structure than less isolated populations. Those studies that covered larger areas also tended to report longer maximum movement distances – a pattern with implications for the design of mark-recapture studies. Caution should be exercised in the application of the metapopulation approach to amphibian population conservation. Some amphibian populations are structured as metapopulations – but not all.

Dispersal and the metapopulation paradigm in amphibian ecology and conservation : are all amphibian populations metapopulations?

Terrestrial habitats surrounding wetlands are critical to the management of natural resources. Al- though the protection of water resources from human activities such as agriculture, silviculture, and urban development is obvious, it is also apparent that terrestrial areas surrounding wetlands are core habitats for many semiaquatic species that depend on mesic ecotones to complete their life cycle. For purposes of conser- vation and management, it is important to define core habitats used by local breeding populations surround- ing wetlands. Our objective was to provide an estimate of the biologically relevant size of core habitats sur- rounding wetlands for amphibians and reptiles. We summarize data from the literature on the use of terrestrial habitats by amphibians and reptiles associated with wetlands (19 frog and 13 salamander species representing 1363 individuals; 5 snake and 28 turtle species representing more than 2245 individuals). Core terrestrial habitat ranged from 159 to 290 m for amphibians and from 127 to 289 m for reptiles from the edge of the aquatic site. Data from these studies also indicated the importance of terrestrial habitats for feed- ing, overwintering, and nesting, and, thus, the biological interdependence between aquatic and terrestrial habitats that is essential for the persistence of populations. The minimum and maximum values for core hab- itats, depending on the level of protection needed, can be used to set biologically meaningful buffers for wet- land and riparian habitats. These results indicate that large areas of terrestrial habitat surrounding wetlands are critical for maintaining biodiversity.

/pdf/biological-criteria-for-buffer-zones-around-wetlands-and-1of77ixc63.pdf

Biological Criteria for Buffer Zones around Wetlands and Riparian Habitats for Amphibians and Reptiles

Free-ranging, sexually mature meadow voles (Microtus pennsylvanicus) were tracked by using radiotelemetry from June through August in Front Royal, Virginia, U.S.A. Estimates of intraspecific spacing were derived from the concurrent movements of up to 16 voles. Positions were recorded hourly for 24 h, twice per week. A total of 16 male and 15 female voles were studied during sixteen 24-h sessions. The daily ranges of males (192.3±109.7 m2) were larger and more variable than those of females (68.6±39.4 m2). Males also changed locations more frequently (Fig. 2). Adult females usually maintained territories free of other females; males overlapped considerably among themselves (Fig. 2). Males temporarily moved into the areas occupied by estrous females, indicating intrasexual competition among males for access to receptive females (Fig. 3). 
M. pennsylvanicus appears to be promiscuous, is socially organized into territorial, maternal-young units during the breeding season, and fits the female territorial model of population regulation.

Space use and social structure in meadow voles, Microtus pennsylvanicus

Current theory and supporting data regarding population regulation and cycling in microtine rodents needs to be reviewed in light of a new, season-sensitive model of social behavior for meadow voles, Microtus pennsylvanicus . The finding of a clear social imperative among meadow voles during most of the fall, winter and spring conflicts with the prediction of high levels of social intolerance in the higher density populations commonly existing late in the year. The general rarity of adult dispersal, except during periods of declining densityin winter and early spring, and the contact-seeking nature of this dispersal,are generally contradictory to predictions based on “intrinsic’ theories. Finally,published data on meadow vole reproduction, recruitment and dispersal, and hence demography, are probably biased as a result of effects produced by the spread of rodent pheromones by investigators, prolonged entrapment of individual voles, and inappropriate behavioral measures in the field.

Seasonal Changes in Reproductive Tolerance, Spacing, and Social Organization in Meadow Voles: A Microtine Model

The Emigration of Radio-Implanted Spotted Salamanders, Ambystoma maculatum

A small population of meadow voles (Microtus pennsylvanicus) in a field enclosure was studied from August to February in Apalachin, New York, USA. Radiotelemetry provided direct measures of intraspecific spacing and social nesting through the fall-winter transition. Data on weather and predation were collected concurrently. A total of 32 voles were radiotracked during 6 tracking sessions, with an average of 17.3 voles (11 to 25 range) tracked per session (Figs. 1, 2a). Discrete social nesting “constellations” first occurred during October, primarily as a result of the formation of extended maternal families (Figs. 1, 2e). Recruitment of adult males and offspring into these early nesting groups was male biased. The average number of voles in these groupings varied from 3.2 (Jan; 3–4 range) to 7.0 (Oct; 4–10 range); but the average number of voles that slept together at any given time, the nesting “cluster,” remained steady at 2.4 (2–5 range) (Fig. 2e). During late December and early January under the protection of snow, many voles shifted their home areas and nesting affiliations with the result that non-lineage nesting constellations formed (Fig. 1, 3). The thermoregulatory benefits of huddling and the threat of predation appear to be important governors of movement, group formation and dispersion. The existence of an optimum group size produces and “Allee Effect” that may contribute importantly to population lows and multi-annual cycles.

Dynamics of social nesting in overwintering meadow voles (Microtus pennsylvanicus): possible consequences for population cycling

Free-ranging pine voles (Microtus pinetorum) were radiotracked on four separate occasions between August 1980 and July 1981 in an apple orchard in Ulster County, New York USA. Positions were recorded hourly for a total of five 24-h periods during each of the four telemetry sessions. A total of 76 voles were radiotracked 
$${\text{(}}\bar x = {\text{19/session)}}$$

 over the course of the study. Pine voles existed in non-overlapping extended family units with a mean of 4.2 (range 2–9) individuals per unit (Figs. 1 and 3). All family members utilized one or two nest sites within the group's exclusive territory (Fig. 2), regardless of sex or reproductive condition. Home range areas (range=6 m2–102 m2) estimated for males and females were not significantly different. Based on telemetry revealed associations between reproductively active individuals, the pine vole mating system appears to be monogamous. However, cooperative polyandry in multi-male units is a distinct possibility.

Dale M. Madison

Papers

Space use and social structure in meadow voles, Microtus pennsylvanicus

Seasonal Changes in Reproductive Tolerance, Spacing, and Social Organization in Meadow Voles: A Microtine Model

The Emigration of Radio-Implanted Spotted Salamanders, Ambystoma maculatum

Dynamics of social nesting in overwintering meadow voles (Microtus pennsylvanicus): possible consequences for population cycling

Social organization of a free-ranging population of pine voles, Microtus pinetorum