02334nas a2200193 4500008004100000245014700041210006900188300001500257490000700272520166900279653002001948653001601968653002001984653002202004100001602026700001702042700001502059856006602074 2011 eng d00aHistorical processes and landscape context influence genetic structure in peripheral populations of the collared lizard (Crotaphytus collaris)0 aHistorical processes and landscape context influence genetic str a1125 -11360 v263 a

Populations at the periphery of a species’ range often show reduced genetic variability within populations and increased genetic divergence among populations compared to those at the core, but the mechanisms that give rise to this core-periphery pattern in genetic structure can be multifaceted. Peripheral population characteristics may be a product of historical processes, such as founder effects or population expansion, or due to the contemporary influence of landscape context on gene flow. We sampled collared lizards (Crotaphytus collaris) at four locations within the northern Flint Hills of Kansas, which is at the northern periphery of their range, to determine the genetic variability and extent of genetic divergence among populations for ten microsatellite loci (n = 229). We found low genetic variability (average allelic richness = 3.37 ± 0.23 SE; average heterozygosity = 0.54 ± 0.05 SE) and moderate population divergence (average FST = 0.08 ± 0.01 SE) among our sample sites relative to estimates reported in the literature at the core of the species’ range in Texas. We also identified differences in dispersal rates among sampling locations. Gene flow within the Flint Hills was thus greater than for other peripheral populations of collared lizards, such as the Missouri glade system where most of the mesic grasslands have been converted to forest since the last glacial retreat, which appears to have greatly impeded gene flow among populations. Our findings signify the importance of considering landscape context when evaluating core-peripheral trends in genetic diversity and population structure.

10aCollared lizard10aFlint Hills10aMicrosatellites10atallgrass prairie1 aBlevins, E.1 aWisely, S.M.1 aWith, K.A. uhttps://link.springer.com/article/10.1007%2Fs10980-011-9631-102777nas a2200217 4500008004100000245014600041210006900187300001300256490000700269520205800276653002502334653000902359653001602368653001202384653002402396653002002420653002202440100001602462700001502478856006602493 2011 eng d00aLandscape context matters: local habitat and landscape effects on the abundance and patch occupancy of collared lizards in managed grasslands0 aLandscape context matters local habitat and landscape effects on a837 -8500 v263 a

The distribution and abundance of a species may be simultaneously influenced by both local-scale habitat features and the broader patch and landscape contexts in which these populations occur. Different factors may influence patch occupancy (presence–absence) versus local abundance (number of individuals within patches), and at different scales, and thus ideally both occupancy and abundance should be investigated, especially in studies that seek to understand the consequences of land management on species persistence. Our study evaluated the relative influences of variables associated with the local habitat patch, hillside (patch context), and landscape context on patch occupancy and abundance of the collared lizard (Crotaphytus collaris) within tallgrass prairie managed under different fire and grazing regimes in the northern Flint Hills of Kansas, USA. Using a multi-model information-theoretic approach that accounted for detection bias, we found that collared lizard abundance and occupancy was influenced by factors measured at both the local habitat and landscape scales. At a local scale, collared lizard abundance was greatest on large rock ledges that had lots of crevices, high vegetation complexity, and were located higher up on the hillslope. At the landscape scale, collared lizard abundance and occupancy were both higher in watersheds that were burned frequently (1–2 year intervals). Interestingly, grazing only had a significant effect on occupancy and abundance within less frequently burned (4-year burn interval) watersheds. Our results suggest that, in addition to the obvious habitat needs of this species (availability of suitable rock habitat), land-management practices have the potential to influence collared lizard presence and abundance in the grasslands of the Flint Hills. Thus, mapping the availability of suitable habitat is unlikely to be sufficient for evaluating species distributions and persistence in such cases without consideration of landscape management and disturbance history.

10aCrotaphytus collaris10afire10aFlint Hills10aGrazing10aHabitat suitability10aLand management10atallgrass prairie1 aBlevins, E.1 aWith, K.A. uhttps://link.springer.com/article/10.1007%2Fs10980-011-9612-402644nas a2200157 4500008004100000245013800041210006900179260004300248490001400291520206700305653002502372653002202397100001602419700001502435856003602450 2010 eng d00aInfluence of landscape context on patterns of occupancy, abundance, and gene flow among collared lizards in the Flint Hills of Kansas0 aInfluence of landscape context on patterns of occupancy abundanc aManhattan, KSbKansas State University0 vMS Thesis3 a

Organisms exist within complex landscapes, and landscape features may influence multiple aspects of a species’ distribution within the landscape, including patch occupancy, abundance within patches, and population genetic diversity at a local or regional scale. We took two approaches to identify the relative importance of landscape context for populations of the Eastern Collared Lizard (Crotaphytus collaris collaris) in the northern Flint Hills of Kansas. First, we conducted surveys at limestone outcrops in experimental watersheds managed under different burning and grazing practices. Habitat occupancy and lizard abundance were estimated by constructing models that incorporated aspects of the environment at multiple scales. Both abundance and occupancy were higher on rock ledges that had more crevices, greater complexity in vegetation, covered a larger area, and were more prominent than available habitat. Abundance and occupancy were also higher in watersheds that were burned frequently (1–2 year intervals), but grazing only had a significant effect in less frequently burned (four–year burn interval) watersheds. Our second approach was to measure genetic diversity and population genetic differentiation and relate these measures to differences in landscape context. We sampled collared lizard DNA at four locations (sample sites < 45 km apart) and analyzed trends in 10 polymorphic microsatellite loci. We found evidence for low genetic variability and moderate population differentiation among our sample sites relative to estimates reported in the literature at the core of the species’ range. Differences in migration rates and ancestry among sampling locations also appear to correspond to differences in landscape resistance based on land cover and rock availability. Thus, it appears that habitat management may influence the suitability of habitat patches at the local scale, and that differences in land cover and rock availability may influence the connectivity of populations at the landscape scale.

10aCrotaphytus collaris10alandscape context1 aBlevins, E.1 aWith, K.A. uhttp://hdl.handle.net/2097/3911