vertical diversity (stratification) & snags the niche species differ in the breadth of their...

Survey of Wildlife-Related Recreation

1955…. 1980 1985 1991 1996

10% 10% ($ 8.5B)

9 % ($10B)

7% ($12B)

7% ($17B)

18% 25% ($17B)

26% ($28B)

20% ($25B)

18% ($36B)

??? 49% ($ 4B)

74% ($14B)

39% ($18B)

31% ($29B)

Vertical Diversity (Stratification) & Snags

The Niche

• Species differ in the breadth of their niche,

euryphagous = wide diet

stenophagous = narrow diet

generalists vs. specialists

ecotones, coverts, edges

The “Edge Effect”

habitat interspersion –

Leopold’s Law of Interspersion

Habitat Fragmentation

1) gap formation

2) decrease patch size

3) increase isolation

4) increase edge

5) conversion of matrix

Countering Edge Effects & Habitat Fragmentation

• Develop connective corridors

• Increase edge complexity

Roads: Formation of Barriers in Landscapes

Animal Movements

- refers to the minimum area needed for an individual to meet all of its normal life requirements

• Concept of the home range

- any part of a home range that is defended intra-specifically, is a territory

(reducing competition, population regulation, spread risk)

Animal Movements

1) Dispersal = 1-way movement (emmigrant vs. immigrant)- typically includes juveniles leaving natal

home range

Types:

Animal Movements

1) Dispersal = 1-way movement (emmigrant vs. immigrant)- typically includes juveniles leaving natal

home range

Types:

2) Migration = round-trip movement- altitudinal & latitudinal; movement to breeding

and wintering grounds

Mortality

1) Predation2) Habitat Loss3) Disease (e.g. bovine tuberculosis, botulism,

pollutants)

4) Hunting & Trapping

MortalityTypes:

1) additive mortality: mortality factors interact in additive manner

e.g., hunting mortality + mortality from predation

2) compensatory mortality: total mortality unchanged despite multiple mortality factors…“mortality factors offset one another”

e.g., less disease mortality with increased huntingharvestable surplus

Managing Overabundant WildlifeCanada goose• Resident, giant Canada geese (“golf course

geese”)• Complaints, disease

Managing Overabundant WildlifeCanada goose

* harvest controlled by:- length of season- bag limits- hunting dates- harvest quotas

* Michigan Canada geese = 1) Mississippi Valley Population (MVP) 2) Southern James Bay Population

(SJBP) 3) local giant Canada geese (early/late

hunt)(“golf-course geese”)

Zone Dates Bag Limit

Possession

North 1-10 Sept 5 10

Middle &

South1-15 Sept 5 10

All zones

20 Sept – 10 Oct, 4-12

Dec2 4

South 1-30 Jan 5 10

Early Season

Regular Season

Late Season

Biodiversity Hotspots

Check link on BIO 240 Web Page --- learn about different sites around the world

Reintroductions & Translocations

Continue to be an important tool in wildlife management

Wildlife Reintroductions• Does habitat

remain?– How much?– Connected?– Management?– Competition /

Predation / Diseases

Wildlife Reintroductions

• Viable Population?– PVA

• VORTEX• RAMAS

Wildlife Reintroductions

• Viable Population?– PVA

• VORTEX• RAMAS• Incorporate GIS

Wildlife Reintroductions• Genetic

Considerations – Why should you care?– Genetic swamping?

Genetic Considerations: Genetic Considerations: Why Should You Care?Why Should You Care?

• Genetic variation is the underlying basis for adaptation to future environmental change

• Loss of genetic variation is often a direct consequence of species reintroduction

• Understanding how genetic loss occurs can help to prevent management actions that decrease the genetic diversity of reintroduced wildlife species

Wildlife Reintroductions• Genetic

Considerations– Inbreeding– Did we release

highly related individuals?

Wildlife Reintroductions• Genetic

Considerations– Founder Effect

Founder EffectFounder Effect

• The reduction in overall genetic diversity experienced as a consequence of population establishment from a limited sample of individuals– Most reintroductions and natural

colonization events exhibit Founder Effects– The magnitude of the effect depends upon

the number of animals translocated or colonizing an area

Wildlife Reintroductions• Genetic

Considerations– Genetic Bottleneck

BottleneckBottleneck

• An event in which a population drops significantly in size and then recovers

• Events such as habitat loss, over harvest, or reintroduction can create bottlenecks and the magnitude of the effect on genetic diversity depends upon:

– Number of individuals at lowest point– Length of time population remains depressed

Genetic DriftGenetic Drift

• Random fluctuations in gene frequencies due to temporal variance in survival and reproduction– Small populations drift more rapidly than large

ones– Higher reproductive and survival rates can

slow the rate of genetic drift– Genetic drift can result in loss of genetic

diversity as well as increases in the frequency of rare alleles

InbreedingInbreeding

• Mating of closely related individuals• Anytime genes that are alike by descent (i.e.,

from a shared ancestor) come together within individuals– Enhanced by slow population growth rates– Affected by mating system– Influenced by the relatedness of the initial

population founders (e.g. reintroductions)

Hypothetical Source Population

Different Colors Represent Copies of Different Genes

Loss of Alleles Due to

Original Sampling

Event

Trap and Transplant

• Small Samples From Source

• Incomplete Sampling of Genes

• Sampling of Related Groups

Reintroduced Population

Loss of Alleles Due to Post-Release

Stochastic Processes

Founder Effects

• Differential Survival of Founders

• Differential Survival of Offspring

• Differential Reproductive Contributions

Genetic DriftInbreeding

Loss of Alleles Due to Stochastic And

Deterministic Processes

Over Generations

• Inefficient Transfer of Genes

• Unequal Reproductive Contributions

• Differential Survival

• Mating of Closely Related Individuals

1010 Generation Bottleneck

Genetic DriftInbreedingLoss of Allelic

Diversity Apparent

20 Generation Bottleneck

20

Genetic DriftInbreeding

Loss of Allelic Diversity Dramatic

Common Allele Predominant

30 Generation Bottleneck

30

Loss of Allelic Diversity Dramatic

Rare Allele Predominant

Wildlife Reintroductions• Genetic

Considerations– Marten

reintroductions