extinction of species exam 2

hybridization

mating between two diff species OR two genetically distinct populations that produces offspring, regardless of fertility of offspring

blue winged warbler plus golden winged warbler =

Brewster's warbler (hybrid)

hybrid zones

areas where two species overlap and interbreed, produce hybrids in these areas

introgression

the incorporation of genes from one population or species to another through hybridization that results in fertile offspring that further hybridize with parental population or species (Backcross)

what effect on genetic material can introgression have over several generations

can result in a complex combination of parental genes, while in simple hybridization 50% of genes will come from each of the two parental species

-genetic homogynization, loss of genetic "purity"

chart in slides ***

F1 hybrid offspring can reproduce with parent populations (backcross, introgression happens here) or with other hybrids to produce F2 hybrids (second generation)

how are hybrid zones maintained? (2 ways)

-hyrbids may be less fit than parental taxa and selected against, but dispersal into the zone maintains a narrow band of F1's (more common phenomenon)

-hybrids may be more "fit" than parental taxa in habitats that are intermediate to parental taxas' native habitat (less common)

t/f hybrid zones are rarely observed in nature

f

detecting hybridization

primarily using morphology until the mid 1960s, but not often effective

-genetic methods have become increasingly important for identifying hybrid individuals

-a simple approach: use a locus where each species has completely different alleles, for example, all individuals in species 1 are AA and all individuals in 2 are aa, hybrid individuals are Aa

how have humans impacted hybridization?

human changes (timber harvesting etc) have resulted in distribution changes and expansions for many species

-species that were isolated now in contact, and more likely to breed

how has the frequency of hybridization changed?

has increased dramatically posing unique practical and philosophical problems for managers

barred owl and spotted owl-- why are the barred owls moving into spotted owl territory?

barred owls have been moving in to spotted owl range as a result of planting trees in formerly treeless areas (irrigation), now making a hybrid with spotted owls (sparred owls)

-concern about the integrity of spotted owl genetic population

the negative view of hybridization

"frequently threatens populations in a wide variety of plant andnaimal taxa bc of various human activites"

positive view of hybridization

"introgressive hybridization may have contributed importantly to generation of species diversity in birds"

genetic extinction

fertile hybrids displace one or both of parentl population through the production of hybrid swarms

hybrid swarm (and an example)

populations or species in which all individuals are hybrids to various degrees

-ex cichlid fish in lake Victoria

why is gentic extinction a big deal

-species and genetically distinct population reflect the product of evolution over hundreds to many thousands of generations

-retaining genetic diversity among species increases evolutionary potential

outbreeding depression

hybrid offspring have lower reproductive success or survival than either parent

female European mink

hybridize with introduced male north American mink

-embryos aborted

-wastage of eggs has accelerated decline of European species

hybridization and speciation (positive side)

-hybridization occurs more frequently than previously thought and is an important source of species

-almost 50 % of plants orginiated from hybridization

-all vertebrates may have gone through an ancient hybridization event

-10% of burd species are believed to hybridize with another speices naturally

hybrid vigor?

-in some cases, hybridization can result in hybrid vigor

-def: offspring of different populations species have high fitness

philosophical issues/questions with hybridization

how much do we want to control in the wild/

should a threatened species be protected if its hybridizaed with a common species?

is it ethical to remove "guilty" species or their hybrid offspring?

should hybirds be allowed to persist if they fill an ecological role?

what constitutes a genetically pure species?

the wolf imbroglio; why did red wolves start breeding w coyotes?

-red wolves are probably a separate species form grey wolves

-historically ranged throughout the SE US, but declined to a few hundred due to persecution and habitat loss

-loss of forested habitat, started breeding with coyotes

red wolf conservation

-removed the last red wolves, only 14 were pure bred

-captive breeding program and wolves were released in north Carolina

-managers "hold" the line at southern border of the refuge by trapping coyotes to prevent further hybridization with red wolves

the new England canid

-eastern wolves were largely eradicated from new England in the 1800s due to habitat loss and persecution

-started hybridizing with coyotes result in the canids

-these canids play a similar role in the ecosystem as a wolves historically, do they merit protection? (keeping ungulate population under control)

hybrid conservation strategy

-due to complexity, there are no formal rules under the ESA; decisions made on case by case basis

-general strategy: remove hybrids when the cause I humans, but leave laone when its natural

-management and conservation is easiest when no introgression occurs; hybrid swarms are a virtually intractable problem

-rapid detection of hybridization and response is critical

conservation genetics

using genetic principles and methods to manage endangered species

topics in conservation genetics;what does conservation genetics seek to do?

-manitaining genetic diversity and adaptibility in small populations

-identification of population bottlenecks

-inbreeding depression and extinction

-management of hybrids

-defining conservation units

one reason why conserving genetic diversity is important?

-maintain adaptability: some alleles that are not currently important could become so as the environment chanhges (emerging diseasaes, pollution, climate change)

-

exmaple of importance of maintaing adaptability in changing environments

resistance to pollutants in tomcod

how to interpret/quantify diversity at the allele level

number of alleles at a locus: if all 4 individuals in a population are AA then there is 1 allele in the population at this locus

-if 1 individual is AA, 2 are Aa, and 1 is aa, then there are 2 alleles in the populations at this locus

heterozygosity

proportion of individuals that are heterozygotes

-if 2 individuas in a population are AA and 2 are aa then what is the heterozygosity?

heterozygosity=0

if i individual is AA, 2 are Aa, and i is aa, then what is heterozygosity

= 0.50

processes that effect levels of genetic diversity in a population

genetic drift, mutation, gene flow

gene flow

exchange of alleles among populations via the movement of individuals

what is the only source of new genetic variation in a population?

mutation

genetic drift

random change in allele frequencies in a population from generation to generation, including the loss of alleles

when is genetic drift weak vs strong?

weaker in bigger populations (1000), stronger in smaller populations (10)

effective population size

-loosely speaking, it is the number of breeders contributing genes to subsequent generations determines how much genetic diversity is lost

what is effective population size reduced by

-unequal reproductive success among individuals

-population fluctuations

-unequal sex ratios

elephant seals Ne:

one male elephant seal mates with many females; Ne is 10x smaller than population size

what is the primary objective of conservation genetics?

identifying populations that have lost genetic diversity

loss of genetic diversity is indicative of what?

population bottlenecks

modern sampling vs historic sampling?

modern: tagging, tracking, methods that dont involve killing?

historic: collecting specimens

patterns in marbled murrelets genetic diversity

general loss in alleles at multiple loci

inbreeding and inbreeding depression

inbreeding is the mating of related individuals, necessarily occurs in small (bottlenecked) populations bc most individuals are related

-inbreeding depression is a redution in the survival or reproductive success that can occur bc of inbreeding

what causes inbreeding depression?

-all organisms have some recessive alleles that are deleterious

-deleterious recessive alleles are masked by dominant alleles in heterozygotes

-deleterious recessive alleles are expressed in homozygous individuals

-inbreeding increases the proportion of the population that is homozygous

symptoms of inbreeding

-low sperm count or abnormally shaped sperm -high infant mortality

-low hatching success

-physical deformities

-compromised immune system and high frequency of disease

conservation strategies for inbred or low diveristy populations

-minimize size of population declines (bottlenecks) and durations

-intentionally mate individuals from genetically distinct poulations (genetic rescue)

how large do populations need to be to avoid inbreeding depression? and why

-an Ne of about 50 is needed to minimize inbreeding depression

-increase in homozygosity when Ne > 50 is slow enough that natural selection can remove deleterious alleles

-increase in homozygosity occurs rapidly in populations of

how large do populations need to be to maintain adaptability?

-some suggest that, in the long term, Ne needs to be 500 to ensure that the loss of genetic diveristy is balanced by new diversiyt form mutations

-but, it could be as high as 5,000 given uncertainty in the mutation rate and what percentage of mutations are beneficial

genetic problems of florida panthers

-florida panthers historically ranged across the SE US - in 1990s only 30 remained

-low genetic diversity, high levels of abnormalities, such as kinked tails, undescended testicles, and cowlicks suggest inbreeding

successful genetic rescue in florida panthers

-8 femlae mountain lions form texas translocated to florida to increase genetic diversity in the mid 1990s

-death rate lower in adult females that were hybrids

-significant population and range expansion (approx 150 individuals currently)

inbreeding may not be a problem? case study of kestrels

mauritius kestrels declined to 4 individuals and have low heterozygosity, but have recovered due to captive breeding and habitat restoration

loss of genetic diversity may not be a problem? case study of elephant seals

-the northern elephant seal was heavily hunted for blubber and by 1910, only 100 northern elephant seals remained on one island off of mexico

-genetic diversity was reduced to very low levels but once harvesting was stopped, populations rapidly recovered (pop now > 150,000)

what makes transloactions difficult? (what do they require)

require:

-availability of appropriate donor populations

-genetic assessments

-capture and transport costs

-long term population and genetic monitoring

can cost millions of dollars and come at the expense of another species

t/f translocations address ultimate causes

f, proximate

how do translocations cause outbreeding depressions in the case of alpine ibex?

-alpine ibex overhunted in europeans alps and augmented by translocations from populations in the sinai peninsula and turkey

-southern ibex breed earlier in the fall and hybrid young were born in the middle of alpine winters

two varying views on private property rights

-intrinsic value: property is a secure natural right, trumps government; protects individual from society

-instrumental: property is a social institution designed to meet society's needs

who benefits from biodiversity? who pays? who controls?

-benefits: society as a whole

-costs: higher for individual landowners

-autonomy: who controls?

US constitution's stance on land rights

-"taking clause" states private property cant be taken for public use without just compensation

-regulations result in taking when they remove all economic uses of a property and landowner has to exhaust all permit opportunities

why are private lands important for conservation?

-over 90% of listed threatened or endangered species have some habitat on private land

-2/3rds of those species depend on private lands for the majority of their habitat

where are most of the protected lands/gov owned lands in the us?

west coast

where are most of the t/e species in the us

hawaii (330)/california (308)

how does the ESA apply to private lands? what sections address this?

-section 7 requires consultations with US FWS when actions on private lands may impact t/e species---> actions cannot result in "jeopardy" or "take"

-section 9 prohibits "takes" of t/e species (although incidental take can be allowed by permit per section 10)

opposition to the ESA

-actual and perceived restrictions on resource use (on public and private lands) continue to fuel resentment towards the ESA

-cream of spotted owl soup

-wolf protests

perverse incentives

when people know a disliked species is about to be listed, they tend to try and destroy all habitat or remaining members of the species before its illegal

creating flexibility in the esa on private lands: safe harbor agreements

landowner agrees with the US FWS to maintain a certain number of individuals of a certain species in exchange for an incidental take permit

creating flexibility in the esa on private lands: habitat conservation plans

landowner develops a plan with the US FWS to offset harmful effects the proposed activity might have on the species and receives an incidental take permit

how much does the DNR control murrelets? how many murrelets are there in listed ranges/worldwide?

WA DNR manages about 10 % of murrelet habitat in WA

-about 600 murrelets nest on dnr lands

-6000 in WA

-15,000 in listed range

-250,00 globally

marbled murrelets vs public school funding?

saving 50 murrelets could cost 50 thousand dollars or this money could be used to pay for public school... tradeoffs...

esa effectiveness?

-criticized bc only 28 of 1400 species have been delisted

-has improved the status of some, not others

-has prevented extinctions; only 9 of 1400 listed have gone extinct (and 6 were probably extinct at the time of listing)

why conserve different groups of individuals?

-conserving morphological and genetic differences among groups of individuals is essential to maintaining adaptability and speciation

-groups of individuals can have unique social or economic value

why is prioritization needed in conservation? how to generally prioritize groups?

-conservation sources are always limited and sometimes only a subset of groups can be protected

-prioritize groups that are "distinct" from other groups - groups that are "not distinct" may be redundant

different types of conservation units (groups for conservation) 5 groups

1. species - groups that cant interbreed (biological def)

2. subspecies - groups below the species level that are "on their way to species-hood"

3. distinct population segments- groups below the species level that are "discrete" and/or "significant" (specific to the endangered species act or ESA)

4. evolutionary significant units- groups below the species level with unique adaptations

5. management units- groups below the species that will not be "rescued" by other groups

what types of conservation units can/cant be listed under the esa?

can: species, subspecies, distinct populations

cant: evolutionary significant units, management units

species as "units" for conservation

-preventing individual species from going extinct is the overarching goal of conservation

-species can be listed under the esa and receive considerable protection

-identifying species is challenging

-groups of individuals that are highly genetic differentiated are unlikely to interbreed (ie, not the species under the biological species concept)

genetic information and cryptic species

-genetic information has been critical for identifying cryptic species that are morphologically similar to a second species

-african forest elephant (vs african bush elephant) was a cryptic species...hard to miss, but it was

gunnison sage grouse and greater sage grouse

-genetic analysis showed the the gunnison sage grouse and the greater sage grouse were very different

-gunnision species only found in colorado

-designation as a species increases conservation attention; can be listed under esa

illegal harvesting in japan?

-japan allowed to harvest southern minke whales under its scientific whaling program

-long suspected that banned species were being harvested

-dna from 50% of whale meat purchased in japanese markets matched dna from humpback whales, fin whales, and dolphins

-2 individuals likely represented an undescribed species

classifying subspecies

-many vertebrates species have been classified into multiple subspecies (on their way to speciation)

-historically, subspecies designations were based on morphology, and more recently, genetic distinctiveness

-designation vary based on taxa and the philosophy of taxonomists

-subspecies can be listed under the esa but no formal esa definition exists

-listings of subspecies are often highly controversial

distinct population segments and their 2 criteria

DPS are defined by policy under the ESA-- 2 criteria include

-discreteness: how different is the population (group) from the rest of the species? (includes differences in genetics, morphology, physiology, ecology, or behavior as well as international differences in threats and conservation practices

-significance: how important is the population (group) segment to the species to which it belongs? ( occurrence in an unusual "ecological setting," loss of the DPS would result in a significant gap in the range;; differs markedly from other populations of the species in its genetic characteristics)

distinct population segments of marbled murrelets

-department of the interior decided to use factors other than genetic data that DPS status was warranted

-the presence of an international boarder and weaker regulations in canada was considered sufficient

-restrictions on harvesting old-growth forests in the pacific northwest remain in place

evolutionary significant units

-preserving the evolutionary potential of a species requires conserving groups with unique adaptations

-ESUs are groups that contain local adaptations not present in other groups

-identifying important adaptive differences among groups using morphology is difficult

-instead, conservation geneticists determine whether populations should be treated as separate ESUs based on for example the presence of unique alleles

management units

-some populations are isolated and will not be re-established naturally by immigration if they go extinct

-such populations are often treated as separate management units distinct from other populations

-genetic criteria are commonly used to define management units

-populations that exchange few individuals (Low gene flow)tend to be genetically different

-popuations that are genetically different are often defined as separate management units

-genetic info can also be used to determine impacts of harvesting to management units

-in mixed stock fisheries, the MU of origin for harvested individuals is difficult to identify without genetics

freshwater impacts in the Klamath river

autumn 2002, a stunning die-off of chinook salmon related to freshwater conditions

-closed the entire fishery

-did this make sense? are klamath salmon caught throughout these waters or just in the klamath area?

-genotypes of harvested fish can tell you a lot about its MU of origin

subspecies as taxonomic groups

-most vertebrate species have classified into multiple subspecies

-historically, subspecies designations were based on morphology, and more recently, genetic distinctiveness

-divergent opinions on what a subspecies is, which vary based on the philosophy of taxonomists

-one of many definitions: populations partway through the evolutionary process of divergence toward full speciation

what is a guiding principle for a definition of species/subspecies

standard taxonomic distinctions, expertise of the doi and the scientific community concerning the relevant taxonomic group

california gnatcatcher subspecies designations

-3 subspecies identified based on morphology

-coloration on breast appears different in northern "coastal" subspecies- but only one of dozens with strong differences

what has endangered the california gnatcatchers

-90% of southern californias coastal sage scrub has been lost to development

-remnant patches being lost by unnaturally frequent wildfire

-fragmented habitat leads to edge effects (predation) and stochasticity

-ca. 2500 individuals remains

-northern "coastal" subspecies was listed as threatened under ESA in 1993

New CGC research

-new study found no genetic differences among sampled sites across the CGC range using 9 "neutral" loci

-developers sued US FWS to remove CGC from threatened species

-re-analysis (by different scientists) found that 2, maybe 3 loci were different between the northern and the other two species

whats at stake with the new CGC research?

-if the fish and wildlife service agrees, it would open development on 200,000 acres of coastal land (valued at billions of $)

-perhaps the regional extirpation of CGC

summary of the science of CGC genetics

-2, maybe 3, of the 9 genes examined appear different between the northern and other 2 subspecies

-coloration on breast appears different

-coastal subspecies occupies a different ecological setting

in what ways are turtles overharvested

-consumption

-adults

-eggs

-pet trade

yangtze giant softshell

-largest freshwater turtle

-3 individuals remain (IUCN critically endangered)

-captive breeding so far unsuccessful

threats to turtles

-overharvesting/overkill

-habitat loss- destruction, degradation, and fragmentation of wetlands; historical losses greatest in the midwest/california; continusing losses in the south

-pollution- nest predators, disease, exotic species

-climate change- temp dependent sex determination (above 30 c is female, below is male)

blanding's turtle conservation status

-declining populations in many parts of range (habitat loss + predators)

-some states (nebraska) have large populations (100,000), others just 10's

-IUCN- endangered

-being considered for listing as a threatened species by US FWS

-considered threatened or endangered in most states inclusing WI

BLANDING TURTLE status in wi

-2012- department of natural resources review of threatened and endangered species list

-353 occurences across most of state in NHI database

-recommended de-listing of blanding's turtle based on occurence data

what can genetics tell us about turtle conservation?

-what are the effects of human activity on populations (ie genetic diversity) of blanding's turtles?

-are all turtle species (common and rare) affected equally?