Doctor of Philosophy / Department of Biology / Samantha Wisely / Habitat fragmentation and destruction are the most ubiquitous and serious
environmental threats confronting the long-term survival of plant and animal species
worldwide. However, some native or exotic species can take advantages of these
alterations and expand their range, placing endemic species at risk of extinction by
changing the composition of biotic communities and altering ecosystem.
Capybara (Hydrochoerus hydrochaeris) are a widely distributed rodent
throughout most of South and Central America, but restricted to areas of standing water.
As the Gran Chaco ecosystem of Paraguay has been converted from dry tropical forest to
pastureland, I hypothesized that this habitat alteration created potential for invasion by
capybara into newly fragmented areas. I used ecological niche modeling to generate
hypotheses about how the distribution of capybara has been affected by land use change,
and tested those hypotheses with phylogeographic analyses. To understand the
mechanisms that have allowed the invasion, I investigated home range, habitat use and
thermoregulation of capybara via radiotelemetry in a deforested area in which capybara
had recently invaded.
Genetic analyses confirm a rapid range expansion scenario with evidence of
secondary contact between two distinct phylogroups which had previously been disjunct.
Modeling results indicated that conversion of forest to pastureland allowed the expansion
to occur. Capybara selected water significantly more than it was available to them, and
avoided shrub forest. I found a significant positive correlation between body temperature
and distance from water, and a significant negative correlation between distance from
water and Chaco ambient temperature. Capybara proximity to water appeared to be
tightly linked to body thermoregulation. These results suggest that although capybara
have expanded into the Chaco forest as it is converted to pastureland, the presence of
permanent water sources in those pastures are the mechanism that allow capybara to
persist in this habitat.
This is the first study to characterize capybara in a xeric habitat without a year
round water source, and scarce natural grasslands. My results show how anthropogenic
habitat modification has allowed capybara to thrive. Understanding how capybara invade
and utilize the deforested Central Dry Chaco will provide valuable information for the
future management of the species and the Chaco ecosystem.
| Identifer | oai:union.ndltd.org:KSU/oai:krex.k-state.edu:2097/1600 |
| Date | January 1900 |
| Creators | Campos Krauer, Juan Manuel |
| Publisher | Kansas State University |
| Source Sets | K-State Research Exchange |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
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