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排序方式: 共有92条查询结果,搜索用时 459 毫秒
71.
AMANDA L. CROUSE RODNEY L. HONEYCUTT ROBERT A. MCCLEERY CRAIG A. FAULHABER NEIL D. PERRY ROEL R. LOPEZ 《The Journal of wildlife management》2009,73(3):362-367
ABSTRACT We used nucleotide sequence data from a mitochondrial DNA fragment to characterize variation within the endangered Lower Keys marsh rabbit (Sylvilagus palustris hefneri). We observed 5 unique mitochondrial haplotypes across different sampling sites in the Lower Florida Keys, USA. Based on the frequency of these haplotypes at different geographic locations and relationships among haplotypes, we observed 2 distinct clades or groups of sampling sites (western and eastern clades). These 2 groups showed low levels of gene flow. Regardless of their origin, marsh rabbits from the Lower Florida Keys can be separated into 2 genetically distinct management units, which should be considered prior to implementation of translocations as a means of offsetting recent population declines. 相似文献
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C. LOPEZ‐VAAMONDE N. E. RAINE J. W. KONING R. M. BROWN J. J. M. PEREBOOM T. C. INGS O. RAMOS‐RODRIGUEZ W. C. JORDAN A. F. G. BOURKE 《Journal of evolutionary biology》2009,22(5):983-996
Although central to understanding life‐history evolution, the relationship between lifetime reproductive success and longevity remains uncertain in many organisms. In social insects, no studies have reported estimates of queens’ lifetime reproductive success and longevity within populations, despite the importance of understanding how sociality and associated within‐group conflict affect life‐history traits. To address this issue, we studied two samples of colonies of the annual bumblebee, Bombus terrestris audax, reared from wild‐caught queens from a single population. In both samples, queens’ lifetime reproductive success, measured as either queens’ inclusive fitness or as total biomass of queen‐produced sexuals (new queens and males), was significantly positively associated with queen longevity, measured from the day the first worker was produced. We suggest that a positive relationship between reproductive success and longevity was inherited from nonsocial ancestors showing parental care and maintained, at least in part, because the presence of workers buffers queens against extrinsic mortality. 相似文献
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L. D. C. LOPEZ‐PASCUA M. A. BROCKHURST A. BUCKLING 《Journal of evolutionary biology》2010,23(1):207-211
Coevolution commonly occurs in spatially heterogeneous environments, resulting in variable selection pressures acting on coevolving species. Dispersal across such environments is predicted to have a major impact on local coevolutionary dynamics. Here, we address how co‐dispersal of coevolving populations of host and parasite across an environmental productivity gradient affected coevolution in experimental populations of bacteria and their parasitic viruses (phages). The rate of coevolution between bacteria and phages was greater in high‐productivity environments. High‐productivity immigrants (~2% of the recipient population) caused coevolutionary dynamics (rates of coevolution and degree of generalist evolution) in low‐productivity environments to be largely indistinguishable from high‐productivity environments, whereas immigration from low‐productivity environments (~0.5% of the population) had no discernable impact. These results could not be explained by demography alone, but rather high‐productivity immigrants had a selective advantage in low‐productivity environments, but not vice versa. Coevolutionary interactions in high‐productivity environments are therefore likely to have a disproportionate impact on coevolution across the landscape as a whole. 相似文献
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J. B. BENOIT G. LOPEZ‐MARTINEZ N. M. TEETS S. A. PHILLIPS D. L. DENLINGER 《Medical and veterinary entomology》2009,23(4):418-425
This study of the bed bug, Cimex lectularius, examines tolerance of adult females to extremes in temperature and loss of body water. Although the supercooling point (SCP) of the bed bugs was approximately −20°C, all were killed by a direct 1 h exposure to −16°C. Thus, this species cannot tolerate freezing and is killed at temperatures well above its SCP. Neither cold acclimation at 4°C for 2 weeks nor dehydration (15% loss of water content) enhanced cold tolerance. However, bed bugs have the capacity for rapid cold hardening, i.e. a 1‐h exposure to 0°C improved their subsequent tolerance of −14 and −16°C. In response to heat stress, fewer than 20% of the bugs survived a 1‐h exposure to 46°C, and nearly all were killed at 48°C. Dehydration, heat acclimation at 30°C for 2 weeks and rapid heat hardening at 37°C for 1 h all failed to improve heat tolerance. Expression of the mRNAs encoding two heat shock proteins (Hsps), Hsp70 and Hsp90, was elevated in response to heat stress, cold stress and during dehydration and rehydration. The response of Hsp90 was more pronounced than that of Hsp70 during dehydration and rehydration. Our results define the tolerance limits for bed bugs to these commonly encountered stresses of temperature and low humidity and indicate a role for Hsps in responding to these stresses. 相似文献
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PAIGE M. SCHMIDT ROEL R. LOPEZ BRET A. COLLIER 《The Journal of wildlife management》2007,71(3):915-919
Abstract: Free -roaming cats (e.g., owned, semi-feral, and feral) impact wildlife worldwide through predation, competition, and disease transmission. Baseline ecological information necessary for population management is lacking. We radiocollared free-roaming cats (feral, n = 30; semi-feral, n = 14; owned, n = 10) in Caldwell, Texas, USA between October 2004 and November 2005 and compared population demographics among sex and ownership classification. We found ranges and movements declined across ownership classes whereas survival and fecundity increased. Our findings suggest that human interactions (e.g., feeding) may result in high, localized free-roaming cat densities, which may concentrate feral cat impacts and should be considered when evaluating population control strategies. 相似文献