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The Impacts of Habitat Fragmentation on Amphibian Genetics and Health in the Brazilian Atlantic Forest Biodiversity Hotspot.

Record Type:	Electronic resources : Monograph/item
Title/Author:	The Impacts of Habitat Fragmentation on Amphibian Genetics and Health in the Brazilian Atlantic Forest Biodiversity Hotspot./
Author:	Belasen, Anat.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2019,
Description:	176 p.
Notes:	Source: Dissertations Abstracts International, Volume: 81-08, Section: B.
Contained By:	Dissertations Abstracts International81-08B.
Subject:	Ecology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=27815114
ISBN:	9781392511640

The Impacts of Habitat Fragmentation on Amphibian Genetics and Health in the Brazilian Atlantic Forest Biodiversity Hotspot.
Belasen, Anat.

The Impacts of Habitat Fragmentation on Amphibian Genetics and Health in the Brazilian Atlantic Forest Biodiversity Hotspot. - Ann Arbor : ProQuest Dissertations & Theses, 2019 - 176 p.

Source: Dissertations Abstracts International, Volume: 81-08, Section: B.

Thesis (Ph.D.)--University of Michigan, 2019.

This item must not be sold to any third party vendors.

Amphibians are declining worldwide due to emerging infectious disease and habitat modification. Although these stressors overlap in time and space, we know little about their interactions. For example, habitat fragmentation reduces genetic diversity in wildlife, and genetic diversity is correlated with disease resistance according to theoretical and laboratory work. However, little is known about the relationship between genetic diversity and disease incidence in wild populations. In my dissertation, I evaluated the impacts of habitat fragmentation on potential disease susceptibility in amphibians of the Brazilian Atlantic Forest (BAF), one of the most biodiverse but heavily fragmented areas on the planet. In Chapters 2-3, I sampled populations of a widespread coastal frog species (Cycloramphidae: Thoropa taophora) across a set of land-bridge islands that represent 12,000-20,000 year old habitat fragments, which I compared with mainland "control" populations. In Chapter 2, I examined the impacts of overall genetic diversity loss due to long-term isolation on islands on (1) immunogenetic (MHC IIB) diversity and (2) susceptibility to microeukaryote infections in a single host frog species. Contrary to previous studies that found high immunogenetic diversity in genetically impoverished populations, I found that inbred island populations exhibited significantly lower MHC IIB diversity than mainland populations. My results also showed that island populations and MHC IIB homozygotes were subject to more infections by diverse potentially parasitic microbes. In Chapter 3 I examined the relationship between immunogenetics and the assembly and diversity of the host-associated microbiome. I found that microbiome diversity was dependent on MHC IIB genotype, with heterozygotes hosting a higher diversity of potentially beneficial microbes. My results also strongly imply that there are interactions between bacteria and eukaryote microbes in the microbiome which have been overlooked by previous studies that focus only on the bacterial amphibian skin microbiome. In Chapters 4-5, I compared the impacts of two different types of habitat modification in the mainland BAF: (1) ~200 year old forest fragments set in a "sea" of intensive cattle pasture, and (2) shaded cacao plantations that serve as less aversive anthropogenic habitats. I compared frog populations found in both habitat types with "control" populations in continuous preserved forests. I sampled six frog host species to examine how the impacts of habitat modification vary according to species ecology: half of the frogs were high-dispersing habitat generalists and half were low-dispersing habitat specialists. In Chapter 4, I evaluated genetic diversity and isolation across these habitats and species. I found that while only generalist species showed reduced genetic diversity in forest fragments embedded in intensive agriculture, only specialists showed genetic isolation. Populations in rustic agricultural areas exhibited similar genetic diversity as those in preserved forests and relatively low genetic isolation, implying that rustic agriculture is less aversive to sensitive animals. In Chapter 5, I examined immunogenetic diversity and infections in a subset of these populations. I found that across all species, fragmented populations exhibited reduced immunogenetic diversity and increased infections. Immunogenotype influenced infections by both the pathogenic fungus Batrachochytrium dendrobatidis and by apicomplexan blood parasites.Taken together, my results suggest that the impacts of habitat modification on amphibian health are significant, and can include loss of overall genetic diversity, loss of immunogenetic diversity, loss of microbiome diversity, and increased infections. This relationship may help explain the recent rise of infectious diseases in amphibians and other wildlife species worldwide.

ISBN: 9781392511640Subjects--Topical Terms:

516476
Ecology.
Subjects--Index Terms:

Amphibian disease susceptibility

The Impacts of Habitat Fragmentation on Amphibian Genetics and Health in the Brazilian Atlantic Forest Biodiversity Hotspot.
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520 $a Amphibians are declining worldwide due to emerging infectious disease and habitat modification. Although these stressors overlap in time and space, we know little about their interactions. For example, habitat fragmentation reduces genetic diversity in wildlife, and genetic diversity is correlated with disease resistance according to theoretical and laboratory work. However, little is known about the relationship between genetic diversity and disease incidence in wild populations. In my dissertation, I evaluated the impacts of habitat fragmentation on potential disease susceptibility in amphibians of the Brazilian Atlantic Forest (BAF), one of the most biodiverse but heavily fragmented areas on the planet. In Chapters 2-3, I sampled populations of a widespread coastal frog species (Cycloramphidae: Thoropa taophora) across a set of land-bridge islands that represent 12,000-20,000 year old habitat fragments, which I compared with mainland "control" populations. In Chapter 2, I examined the impacts of overall genetic diversity loss due to long-term isolation on islands on (1) immunogenetic (MHC IIB) diversity and (2) susceptibility to microeukaryote infections in a single host frog species. Contrary to previous studies that found high immunogenetic diversity in genetically impoverished populations, I found that inbred island populations exhibited significantly lower MHC IIB diversity than mainland populations. My results also showed that island populations and MHC IIB homozygotes were subject to more infections by diverse potentially parasitic microbes. In Chapter 3 I examined the relationship between immunogenetics and the assembly and diversity of the host-associated microbiome. I found that microbiome diversity was dependent on MHC IIB genotype, with heterozygotes hosting a higher diversity of potentially beneficial microbes. My results also strongly imply that there are interactions between bacteria and eukaryote microbes in the microbiome which have been overlooked by previous studies that focus only on the bacterial amphibian skin microbiome. In Chapters 4-5, I compared the impacts of two different types of habitat modification in the mainland BAF: (1) ~200 year old forest fragments set in a "sea" of intensive cattle pasture, and (2) shaded cacao plantations that serve as less aversive anthropogenic habitats. I compared frog populations found in both habitat types with "control" populations in continuous preserved forests. I sampled six frog host species to examine how the impacts of habitat modification vary according to species ecology: half of the frogs were high-dispersing habitat generalists and half were low-dispersing habitat specialists. In Chapter 4, I evaluated genetic diversity and isolation across these habitats and species. I found that while only generalist species showed reduced genetic diversity in forest fragments embedded in intensive agriculture, only specialists showed genetic isolation. Populations in rustic agricultural areas exhibited similar genetic diversity as those in preserved forests and relatively low genetic isolation, implying that rustic agriculture is less aversive to sensitive animals. In Chapter 5, I examined immunogenetic diversity and infections in a subset of these populations. I found that across all species, fragmented populations exhibited reduced immunogenetic diversity and increased infections. Immunogenotype influenced infections by both the pathogenic fungus Batrachochytrium dendrobatidis and by apicomplexan blood parasites.Taken together, my results suggest that the impacts of habitat modification on amphibian health are significant, and can include loss of overall genetic diversity, loss of immunogenetic diversity, loss of microbiome diversity, and increased infections. This relationship may help explain the recent rise of infectious diseases in amphibians and other wildlife species worldwide.
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