Environmental Engineering Reference
In-Depth Information
future management plans for the conservation of this species on the Pacifi c
coast of South America.
Demographic responses to climate change depend on population
size
The biology of the Steller sea lion,
Eumetopias jubatus
, has been the subject of
intense scientifi c investigation that has resulted
in signifi cant advances in the
understanding of its evolutionary
history and population structure (Baker
et al. 2005, Bickham et al. 1996, 1998, Harlin-Cognato and Honeycuth 2006,
Hoffman et al. 2006, 2009). Harlin-Cognato and Honeycuth (2006) examined
the phylogeographic history of the species in relation to the presence of Plio-
Pleistocene insular refugia. Their results suggest that the genetic structure
of Steller sea lions is the result of
Pleistocene glacial geology, which caused
the elimination and subsequent reappearance of suitable rookery habitat
during glacial and interglacial periods. Five years later, Phillips et al. (2011)
analyzed a large genetic data set consisting of 3 mitochondrial regions for
more than 1,000 individuals in order to better understand the historical
processes that have culminated in the extant populations of
E. jubatus
.
The results of their study describe the role of climate change in shaping
the population structure of the species. Climatically associated historical
processes apparently involved differential demographic responses to ice
ages dependent on population size. Ice ages during times of small effective
population size promoted restricted gene fl ow and fragmentation, and ice
ages occurring during times of large population size promoted gene fl ow
and dispersal. These results illustrate that effective population size has a
profound effect on how species respond to climate change. According to
the authors, the most important aspect of its study is the implication that
the ongoing anthropogenically caused climate change has the potential
to affect distributions and demography of contemporary species in ways
similar to that documented in their study.
Pollutants in Marine Mammals
Wildlife toxicology and sentinel organisms
The fi eld of wildlife toxicology can be traced to the late nineteenth and early
twentieth century. This discipline focuses on the study of the effects that
xenobiotics could have on wildlife and man and led to many investigations
on those pollutants—heavy metals and synthetic pollutants. The use of
sentinel organisms or bioindicator has emerged as the most common
method to determine the presence of pollutants in a given environment.
Such sentinels are used to gain early warnings about current or potential
