Darwin’s finches of the Galápagos Islands are a model system for the study of evolution by natural selection and ecological speciation. Previous studies suggest that selection on bill morphology due to feeding may have secondary consequence on song, an important cue in species recognition. In Chapter 1, I document differences in songs between nine species of Darwin’s finches on Santa Cruz Island. Songs of individuals species are distinct, with sister species having the greatest number of song differences in comparison to species that are further removed phylogenetically. Additionally, differences in song features between species correlate with beak and body size. These results led me to examine song differences within a highly variable population of the medium ground finch, Geospiza fortis, on Santa Cruz Island. The medium ground finch at El Garrapatero, Santa Cruz Island, features large and small beak morphs with relatively few intermediates. As in other Darwin’s finches of the Galápagos Islands, these morphs presumably diverged in response to variation in local food availability and inter- or intra-specific competition. In Chapters 2--4, I address whether the two beak morphs produce distinct mating signals (songs), mate assortatively, and have higher fitness than intermediate sized birds (e.g., produce more offspring). I find that birds with longer, deeper, and wider beaks (large morphs) produce songs with significantly lower minimum frequencies, maximum frequencies, frequency bandwidths, and vocal performance. The two morphs show strong positive assortative pairing, a pattern that holds over three breeding seasons and during both dry and wet conditions. In addition, there is reduced gene flow between the morphs, as revealed by genetic variation at ten microsatellite loci. Documenting offspring success was complicated by the introduction of a parasitic fly, Philornis downsi. Nestlings in nests with P. downsi had extremely high mortality. Parasitism rates were equal across all beak morphs, however the combination of mortality due to both parasitism and predation resulted in fewer small morph fledglings and more large morph fledglings than expected in 2005. In 2006 only two birds fledged, and they were the offspring of a single pair with intermediate sized beaks; the fitness of small and large morphs was zero. Nestling size and growth rates did not differ between parasitized and unparasitized nests. These findings together have interesting implications for speciation and population divergence in this group of birds.

Measures of species, morphological, functional, and ecological diversity are interrelated although not always highly correlated. Morphology tends to influence how organisms function, which in turn influences what they do in their environment. Here I study how morphology, function and ecology relate to one another and to diversity in the Squamata. Squamates have high variability in vertebral number, body shape, and functional and ecological diversity. First, I construct a supertree of the Squamata and use it to study the evolution of presacral vertebral number and its variability in squamates, relating these traits to morphological and species diversity. Squamate lineages vary in the modal number and degree of variability in number of vertebrae. Most lineages with increased variability, or relaxed constraint, on vertebral number have diversified more in terms of both species richness and morphological disparity relative to more constrained lineages. Second, I use high speed video data to show that more elongate species tend to bend their bodies more, and species with relatively longer hind limbs tend to take longer, quicker strides, resulting in faster sprinting in the elongate genus Lerista and the stocky phrynosomatines. However, differently shaped species in these two clades do not select different substrate characteristics or perform differentially on sand versus sandpaper substrates. Third, conducting a morphometric analysis of the Phrynosomatidae, I show that the horned lizards (genus Phrynosoma ) have undergone continued directional evolution towards increasingly stocky body shapes. In addition, species that are stockier also run more slowly, have relatively longer horns for predator defense, and are increasingly specialized on an ant diet. Phrynosomatid morphology, locomotor function and ecology have co-evolved extensively. When all of my findings are considered, there is evidence that a relaxation of constraint on presacral vertebral number is a key innovation in squamates. Relaxation of constraint facilitates the evolution of more diverse body shapes through changes in vertebral number, and this increased diversity of body shapes allows for the invasion of new niches through increased functional diversity. Ultimately, these factors enhance diversification in lineages with high variability in vertebral number.

Marine derived biomass from salmon carcasses is incorporated into coastal Pacific Rim salmon river systems via the organisms and structures of the freshwater foodweb. In brown water rivers of Western Kamchatka, the foodweb is dominated by ubiquitous benthic amphipods (Anisogammarus kygi) that consume salmon carcass material. We hypothesized that A. kygi are a strong interactor in the feedback loop which links dead spawner biomass to juvenile salmonid growth. We found that A. kygi had a complex life cycle with anadromous and resident forms. A. kygi dominated the macro-benthos, comprising more than 88.0% (SE=.01, N=7) of invertebrate biomass, and were highly mobile within the system, exhibiting upstream migrations of ovigerous females (23 ind/m3 ± 5), drift of juveniles, and re-distribution during carcass loading. A. kygi was observed feeding on 97% of salmon carcasses examined (N=100), making up 98.8% (SE .007) of invertebrate consumers, at densities up to 3,000 carcass-1. Amphipods were an important food item for rearing salmonids, especially during the summer when fish diets reached a peak of 88.7% (SE=6.0%) amphipods in 2005, and 68% (SE=18%) amphipods in 2006. The condition factor of salmonid juveniles (K) increased from spring to summer, particularly in juvenile chum, whose spring diet was 76.83% (SE 0.05) amphipods, corroborating the importance of an amphipod based diet for salmonids in this river. We concluded that A .kygi is a strong interactor in the Utkholok system. We also observed abundance of A. kygi in six other brown water rivers of western Kamchatka which suggests that the amphipod-mediated feedback of marine derived nutrients described for the Utkholok, is typical of brown water systems with salmon.

The concept of geographic variation in phenotypes has a long history in evolutionary biology. Differences in phenotypes can stem from both local adaptation, in which differentiation occurs at the genetic level, and phenotypic plasticity, in which differentiation is a direct effect of an animal's environment. Although not mutually exclusive, each of these pathways contributes to organismal fitness. I examined the effects of environmental factors, including development, temperature, latitude, altitude, and habitat structure on the growth, body morphology and performance of two terrestrial ectotherms. Eleutherodactylus coqui is a direct-developing frog whose life history lends itself to studies of development, and Sceloporus occidentalis is a wide-ranging temperate lizard suited for studies of geographic variation. In the laboratory, I manipulated the development of these ectotherms either by introducing a predation threat or by varying incubation temperature. I then examined the effects of these factors on the animals' phenotype at hatching and, in the case of S. occidentalis, for a number of weeks thereafter. This design allowed me to test the persistence of phenotypic plasticity. Finally, I measured the correlations among morphology, performance and habitat use in four wild populations of lizards. I found that hatching early in response to predation can have dramatic effects on the morphology and performance of E. coqui froglets: animals that hatch early to escape predation suffer a decrease in jumping ability, resulting in a trade-off between life history stages. In S. occidentalis, incubation temperature affects morphology and performance over time, but some morphological characteristics that contribute to performance capacities, such as hindlimb length, vary instead across latitudinal and altitudinal gradients. Finally, despite morphological and performance differences among populations of wild-caught lizards, S. occidentalis represents a generalized species that can utilize many different habitat types without large corresponding changes in body form. Here I argue that developmental responses to the environment can be adaptive, but also that traits that have direct effects on fitness tend to be more canalized in these animals. Further studies on geographic variation should include both of these factors when determining the evolutionary history and possible evolutionary trajectory of ectotherms.

Many benthic fishes use their pectoral fins for both swimming and substrate contact. Each behavior imposes different, potentially conflicting functional demands on the pectoral fins. It has been hypothesized that benthic fish decouple these demands through morphological and functional regionalization of the fins, but this hypothesis had not been experimentally tested. In this study, I demonstrated functional regionalization of the pectoral fin in the longhorn sculpin, Myoxocephalus octodecimspinosus, a benthic scorpaeniform fish. The ventral region of the pectoral fin is used during substrate contact; the dorsal region is used during swimming. I characterize a previously undescribed swimming behavior during which the pectoral fins are held in a steady, laterally extended posture while the dorsal, anal and caudal fins are used for propulsion. I also investigate the functional morphology of individual pectoral fin rays. I find that the curvature of the fin rays is higher in the ventral versus dorsal region of the fin, regardless of behavior. The fin rays of longhorn sculpin possess a previously undescribed morphology in cross-section. Specifically, the hemitrichia, or bony halves that make up the fin rays, are cylindrical in cross-section proximally and crescent-shaped distally. The cylindrical segments in the proximal regions of the fin rays of longhorn sculpin provide resistance to bending, which may confer strength and support for weight-bearing substrate-contact behaviors. Further, the ventral fin rays, which are used for substrate contact, have a higher proportion of their total length made up of cylindrical segments. Finally, I used a comparative approach to examine the distribution of morphological specializations and habitat (benthic or pelagic) of the pectoral fins among scorpaeniform fishes. I identified three discrete characters of the pectoral fins that are associated with a benthic habitat for analysis; (1) an asymmetrical fin membrane among ventral fin rays, (2) the presence of fin rays that are unbranched distally, and (3) the presence of ventral pectoral fin rays that are free of fin membrane. Each of these characters has evolved more than once among scorpaeniform fishes and is more common among benthic than pelagic fishes.

No description available.

Wood turtles (Glyptemys insculpta) are of conservation interest rangewide. Anecdotal accounts demonstrate that some populations have been decimated since 1850, and recent studies demonstrate that declines are still underway. From 2004–2008 I investigated the ecology of wood turtles in Massachusetts and New Hampshire. I obtained between one and five years of annual home range data for 150 turtles, and evaluated population structure at 31 sites in five major watersheds. Seasonal floods displaced 7% of wood turtles annually in one watershed, and accounted for elevated mortality. Twelve wood turtles were displaced < 16.8 km, and two were displaced over a 65-foot dam. Several turtles overwintered at their displacement site and two returned successfully, indicating that floods are a mechanism of population connectivity. Several homing turtles ended up in new areas. Turtles occupied stream segments with gradient < 1%, lower than generally available. Agricultural machinery accounted for most observed mortality, followed by automobiles and mammals. Female turtles exhibit smaller home ranges in agricultural areas. Older turtles move farther from the river than do young turtles, possibly reflecting their familiarity with a former landscape. Population density ranged from 0–40.4 turtles/river-kilometer. The highest densities occur in central New Hampshire and lower densities occur in the Housatonic watershed. Population density is negatively correlated with agriculture at both riparian and watershed scales, and responds unimodally to forest cover. Wood turtle populations in western Massachusetts are declining by 6.6–11.2% annually. I estimated ages of turtles by assessing shell-wear rates from photographs. Wood turtles regularly achieve ages over 80 years, and like related species, do not exhibit clear signs of senescence. Old wood turtles are reproductively dominant, and their survival rates are twice as high as young turtles. Carapace scutes appear to require 80 years to become worn. Population modeling indicates that wood turtle populations are declining in New England due to anthropogenic and natural factors. Conservation efforts must address the effects of agriculture on adult survival. Climate change may negatively affect northeastern wood turtles through increased flooding. Populations in mountainous areas may be likely candidates for conservation because they don't occupy prime agricultural land, but may be more susceptible to floods.

No description available.

No description available.

No description available.