Ecology & Environmental Problems

Dr. Ron ChesserLecture #17

Conservation, Endangered Species #2Reading: Chapter 13, 14

Exam II FAUX PAUX

Form #1 – Questions #29 &30 were mis-graded (e & d are correct)

Form #2 – Questions are all correctly graded

Form #3 – Question #14 mis-graded (c is correct)

Average grade ~76%

Competition

Domestic species compete with native fauna and flora

Man sometimes utilizes the same food resources (fish, game)

Man sometimes utilizes the same space– Habitat exclusion

Introduction of Exotic Species Non-native species may

outcompete the native taxa Sometimes purposeful

sometimes accidental– Asian clam– Tumbleweed– Pheasant– Insects– Nutria

Hunting/exploitation & Sport Carrier Pigeon Dodo Whales Bison (American & European) Seals But consider – Pere David’s Deer

Hunting is not currently a major contributor to endangered species– Regulations– Limits– Enforcement & Economic input

Conservation Considerations

Population Risk factors Environmental Risk Natural Catastrophe (isolation) Genetic Risk

Conservation Considerations

Population Risk Factors– Mating success – Birth rates (fertility & fecundity)– Death rates– Variation in population demography– Growth curves in reverse

Conservation Considerations

Environmental Risk– Predator – prey relationships– Local endemism and extinction risk– Generalists versus specialists– Mechanisms to withstand environmental

variationsHibernation, torpor, seed banks, sperm storage,

superfetation, multiple paternity (polygyny & polyandry), environmental triggers

Diversity and Environment

Where is diversity greatest?– Tropics– Temperate forests– Deserts

Why do habitats vary?

Succession Seres Grasslands versus forests

Conservation Considerations Natural Catastrophe

– Isolationism, endemism and extinction risk

– Zoos and wildlife reserves

Conservation Considerations Genetic Risks

– Inbreeding– Reduced Adaptability– Genetics & Behavior– Behavioral Ecology– Related species and genetic

identity– Effective Population Size– Spatial heterogeneity

Genetic Characteristics Homozygous means having inherited the same "gene" for a particular trait from

both parent. Inbreeding increases homozygosity by "fixing" a particular trait. Purebred animals display a high degree of homozygosity compared to mixed breeds and random-bred animals. The idea of purebred animals is that they should "breed true". When one purebred is mated with another of the same breed, the offspring will have uniform characteristics and will resemble the parents.

Heterozygous means having inherited a different gene for a particular trait from each parent. For example one gene of long fur (recessive) and one gene for short fur (dominant). 50% of a heterozygous individual's offspring will inherit one form and 50% will inherit the other. Carefully controlled "out-crossing" increases heterozygosity for selected traits by introducing new genes into the hybrid offspring.

Heterosis is the scientific term for hybrid vigor. It is possible that there are "bad" genes which produce less vigorous individuals when in the homozygous state because good genes have been bred out along with the undesirable characteristics; theoretically the bad genes could be bred out, but in practice this doesn't seem to happen. The other theory is simply that you simply need to have a mixture of two different genes to get the desired effect as they somehow complement each other; highly inbred animals lack this diversity and have poorer immune systems.

Inbreeding Inbreeding is breeding between close relatives. If

practiced repeatedly, it leads to a reduction in genetic diversity. Inbreeding often leads to reduced health and fitness (called consanguinity depression); however, livestock breeders often practice inbreeding, then cull unfit offspring, especially when they are trying to establish a new and desirable trait in their stock.

Within humans, the genetic problems caused by inbreeding is believed to be a factor in the prohibition against incest.

Inbreeding occurs in animals. For example, the cheetah is a highly inbred species, probably because of a population bottleneck in the species' recent past. Inbreeding is also deliberately induced in laboratory mice in order to guarantee a consistent and uniform animal model. Human genetic diversity is also limited, indicating a population bottleneck some 100,000 years ago

Uncle & Niece are expected a child – the uncle’s half brother has a genetic diseaseTo determine the (?)s risk for the recessive illness, count the arrows tracing the

descent of the allele through both of its parents.    

                                                                                                                                                       The risk = (1/2)5, or 1/32. Compare this risk with the general population risk of about 1/40,000 for this condition. This illustrates how a sizeable proportion of parents of children with rare recessive problems are consanguineous (blood-related).

Black and White Ruffed Lemur

Red Ruffed Lemur

Behavioral EcologyPOLYGYNY (POLYGAMY)POLYANDRYPHILOPATRYFIDELITYDISPERSALSNEAKY BREEDERS (SF)

Habitat Fragmentation

Habitat Fragmentation

Playa Lakes & Fragmentation

VagilityVolant

The Dilemma of Small Populations

Effective Population Size (Ne) – The number of randomly mating individuals in a population that would cause the change in inbreeding at the same rate as the one in question.

ΔF = 1/(2 Ne)

Populations with small Ne have rapid rates of inbreeding

Small populations lose genetic variation rapidly

Solutions?

The Frozen Zoo Zoo Management Artificial Insemination Corridors (of dispersal) Artificial exchange Pedigrees

Buffer Zones

Buffer Zones for runoff prevention

Genes, Society, and Environment

Agriculture and Crop Selection Modern Crop Improvement …

Transgenics BioInformatics Genomics, Proteomics, Metabalomics Gene Expression