Conservation Bio Final Exam

Anna Conservation Focus

increased natural disasters and invasives because European settler foresting practices. High mammalian extinctions.chall

Outbreeding depression

lowered fitness that sometimes occurs when individuals of different subspecies or distinct populations mate and produce offspring

as population size declines, random effects become ___ influential in determining the fate of populations

more

Demographic stochasticity

random variation in birth and death rates among individuals over time in small populations

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* Leads to increased annual variation in population growth rate (and therefore population size) over time
* May lead to skewed sex ratios in the population
* Effects are most pronounced in very small (

Total number of individuals in a species =

sum of all individuals from each distinct population

protecting _____ is the key to preserving species

populations

species extinction probability is related to both __ and __ of remaining populations

number and size

as populations are reduced in ____ and , populations are more likely to go extinct__

number and area

Population Decay

precursor to extinction

* delcines in population size
* local population extinctions
* geographic range contraction

biological annhilation

population decay increases confidence of 6th extinction occurrence

Populations are spatially structured

i.e. big horn sheep -→ metapopulation

Metapopulation

network of subpopulations linked by movement of individuals among them

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local dynamics of each subpopulation are independent

metapopulation persistence is determined by __ and _ of subpopulations

local extinction and recolonization

Metapopulations picture

Source-sink theory

* Model population dynamics in the context of heterogeneous habitats patches
* Habitat quality varies from patch to patch
* Variation in habitat quality affects demographic (births & deaths)

Source

* good habitat quality
* natality > mortality
* r > 0
* demographic excess
* net emigration

Sink

* lower habitat quality
* mortality > natality
* r < 0
* demographic deficit
* net immigration

\
smaller isolated patches are sink habitats

Conservation implications

* The “population” is the key unit of management and conservation focus
* Maintaining more and larger populations reduces extinction risk
* Local extirpation / elimination of local populations should be prevented
* Conserving source populations in high quality habitat is a particularly important conservation measure

Large populations are less or more likely to go extinct?

less

the smaller the population, the ___ the extinction risk

greater

population size and extinction probability are ___ correlated

inversely

Problems of small populations

* Loss of genetic variation (genetic drift)
* Demographic stochasticity
* Environmental stochasticity

In general, the smaller the population becomes, the more influential of random processes become in determining population dynamics

Minimum Viable Population

number of individuals necessary to ensure the long-term survival of a species

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example: 99% chance of remaining extant for 1,000 years

* considers full range of environmental conditions
* requires detailed demographic study of populations

Population Viability Analysis

analytical technique that combines demographic analysis and environmental variation in predicting the probability of population persistence over time (and sometimes under different management scenarios)

* Risk assessment that incorporates demographic and environmental stochasticity
* Simulation approach: run model many times, report probability ranges

PVA output

each line, or population trajectory, represents on simulation

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* they all have crashes and then population increase

Minimum Dynamic Area

area of suitable habitat necessary for maintaining MVP

* puts MVP in spatial context
* estimated by studying spatial ecology and home range characteristics of target species

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Useful in reserve design/planning, particularly when status of species populations are unknown.

Is there a positive or negative association between genetic variation and population size?

positive

measures of genetic variation

* % polymorphic loci
* alleles per locus
* % heterozygosity

Heterozygosity level is lower or higher with smaller population sizes?

Genetic drift

change in allele frequencies and loss of genetic variation in a small population due to the random sampling of the gametes in sexual reproduction

All ___ populations are subject to genetic drift

finite

Genetic drift can alter __*___and cause the loss of___*__

allele frequencies; genetic variation

the magnitude of genetic drift is ___ to the population size

inversely proportional

when the population is _______*, genetic drift has a*__ ______ influence on allele frequencies than selection__

small; greater

What can counter the effects of drift?

Immigration

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* with 1 immigrant per generation, population retains 90% initial heterozygosity

True or false. Natural mutation rates are not sufficient to counter effects of drift

true

Rate of loss of genetic variation is a function of __

effective population size

Effective population size (Ne)

“the number of breeding individuals in an idealized population that would show the same amount of dispersion of allele frequencies under random genetic drift or the same amount of inbreeding as the population under consideration“ (Wright 1938)

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* smaller than actual population size
* not all individuals are reproductively mature
* not all reproductively mature individuals breed each year
* mating is not random/some individuals may have >1 mate

Factors that reduce effective population size

* Wide variation in reproductive output among individuals
* Mating system and/or unequal sex ratio
* Population fluctuations and bottlenecks

Effective population size example

Does sex ratio affect effective population size?

yes.

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overexploitation can alter sex ratios in wild populations

Population bottleneck

radical, short-term reduction in population size leading to lowering of N e and loss of genetic variation

* Greatest when N < 10 individuals for several generations

founder effect

reduced genetic variability present when a new population is established by a small number of individuals

consequences of reduced genetic variability

* Inbreeding depression
* Loss of evolutionary flexibility
* (Outbreeding depression)

Inbreeding

mating of close relatives; offspring alleles are identical by descent

Inbreeding coefficient (F)

ranges from 0 (no inbreeding) to 1 (complete inbreeding, all alleles identical by descent)

Inbreeding depression

the decline in fitness observed in inbred progeny relative to completely outbred individuals

Loss of evolutionary flexibility

* Rare alleles and unique combinations of alleles may confer selective advantages for future set of environmental conditions
* Loss of genetic variability → limits potential response (plasticity) to changing future conditions
* Example: plant response to increasing concentrations of atmospheric gases or toxic metals in soil

vulnerability to demographic stochaticity

* Species with naturally variable birth and death rates (e.g., annual plants, insects)
* Species with inherently low birth rates (populations take longer to recover after a decline)

Allee effect

inability of a species’ social structure or reproductive system to function once a population falls below a certain density or number of individuals

Allee effect examples

* Minimum group size for hunting success (e.g., wild dogs) or anti-predator defense (e.g., musk ox)
* Declines in nesting success of colonial nesting birds (e.g., passenger pigeons and seabirds)
* Difficulty finding mates at low population densities (e.g., tigers)
* Disruption of plant/animal pollination interactions

Environmental stochasticity

random variation in the biological and/or physical environment that increase the risk of extinction in small populations

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* single, catastrophic events may cause local extinctions

biological environmental stochasticity

fluctuation in population size of competitors, predators, or pathogens

Physical environmental stochasticity

variation in precipitation or disturbance events (fire, floods, etc.)

___ stochasticity is generally more important than __ stochasticity in increasing probability of extinction and may affect species with relatively larger population sizes

environmental; demographic

Extinction vortex

genetic restoration

the elimination or reduction of deleterious alleles and recovery to normal levels of genetic variation for a population in poor genetic health by the introduction of individuals from a genetically healthy population

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* florida panther

Florida panther major threats

* Habitat loss and fragmentation
* Road mortality

suffered from inbreeding depression

florida panther management option 1

Remove kittens from Florida population for captive breeding and release program.

florida panther management option 1 advantage

* maintain subspecies integrity
* can select/breed individuals with or without specific traits

florida panther management option 1 disadvantage

* Risk that reintroduced animals won’t be released or survive in the wild.

florida panther management option 2

Artificially restore gene flow into Florida population by introducing Texas pumas (Puma concolor stanleyana)

florida panther management option 2 advantage

* **Potential to purge deleterious traits**
* **Continued incentive for habitat conservation**

florida panther management option 2 disadvantage

Risk of outbreeding depression

Which primary THREATS to biodiversity do protected areas address directly?

overexploitation and habitat loss

Tropical rainforest hotspots

Mediterranean & Temperate hotspots

reserve selection: biodiversity hotspots

peak of species richness in USA

Where does this leave biodiversity coldspots?

* There is no single solution to reserve design/selection
* All areas need biodiversity and functioning ecological systems (regardless of their species richness)!

___ are the highest converted biome

temperate grasslands

Gap analysis

using geographic information systems to select areas of reserve

gap species

one not well protected in any part of its range

conceptual model of gap analysis

principles of reserve design

Four R’s of reserve design

* representation
* preserving all types
* redundancy
* multiple examples of each habitat types
* resiliency
* conserve an area that can recover after disturbances
* reality
* always going to be an impact of a reserve design
* sometimes have to relocate people
* sometimes receive donations or land to conserve

general pattern of a biosphere reserve

Core areas

complete protection in national parks

Buffer zones

sustainable forestry and agriculture

Terrestrial protected areas reduce

deforestation

Protected status affects

deforestation rates

paper parks

areas of land that are designated as protected areas on paper but lack the resources and management necessary to actually provide protection to the wildlife and ecosystems within them

Empty forests

areas of forest that appear to be intact from the outside, but have lost most of their large animals due to hunting and other human activities. These forests may still have trees and smaller animals, but the loss of large animals can have significant ecological impacts.

Resources for ___ are critical for protected areas

enforcement

defaunation

the decline or extinction of animal populations in a particular habitat or ecosystem, often caused by human activities such as habitat destruction, hunting, and climate change.

genetic restoration outcomes

* Reduction in frequency of traits associated with inbreeding in hybrids
* Increased reproduction and survival
* Population increase to >100 within 10 years • Shift in population age distribution
* Increase measures of genetic diversity
* Evidence of range expansion into previously vacant habitats

panther example: do purebred and hybrid panthers survive at different rates?

* Hybrid female survival > purebred
* No difference among males
* Hybrid kittens 3x more likely to reach adulthood than purebreds

Isle Royale

* Critically low numbers of wolves remaining
* High levels of inbreeding
* Low immigration and expected extirpation of wolves
* Remote location and isolation from Mainland
* Declining frequency of ice bridge formation due to climate change
* Low probability of adequate natural colonization to “rescue” population

NEPA

national environmental policy act

What does NEPA require? Isle Royale

that federal agencies (like the National Park Service) explore alternative actions and make their decision-making open to the public.

Actions considered: Isle Royale

A.) No action

B.) Immediate Limited Introduction

C.) Immediate Introduction with Potential Supplemental Introductions

D.) No Immediate Action with Allowance for Future Action

Outcomes of alternative elements : Isle Royale

ex situ conservation

“off site” in captivity

Population Establishment (3)

1. Reintroduction programs
2. Reinforcement/augmentation/restocking programs
3. Introduction programs

Reintroduction Programs

* involve release of individuals into an ecologically suitable site within their historic range
* Individuals may be captive-bred or collected from wild
* Establish new population within native environment

Reinforcement/augmentation/restocking programs

involve release of individuals into existing population to increase its size or alter gene pool

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class examples:

* Florida panther (Puma concolor coryii) genetic restoration
* Isle Royale wolf (Canis lupus) rescue
* Kemp’s ridley sea turtle “headstarting”
* collect eggs and raise hatchlings in captivity before releasing
* “double-clutching” or chick fostering in endangered birds
* collect first eggs laid, female will produce and raise a second clutch
* incubate eggs and raise chicks in captivity
* Potentially doubles reproductive output of a rare female

Introduction programs

* involve releasing animals or plants into ecologically suitable sites outside of historic range
* What conditions justify “introduction?

Reintroduction of wild-caught individuals

* Individuals collected from closest healthy population and translocated to new site
* Screening to ensure genetically diverse “founder” population and select individuals adapted to a similar environment and climate
* Many successful examples:
* Gray wolf (Canis lupus) reintroduction into Greater Yellowstone ecosystem in late-1990’s
* White rhinoceros re-introductions in southern Africa

Isle Royale is a __ release

hard

Yellowstone is a __ release

soft