Ecology & Environmental Problems Dr. Ron Chesser Lecture #17 Conservation, Endangered Species #2...
-
Upload
hilda-miller -
Category
Documents
-
view
215 -
download
0
Transcript of Ecology & Environmental Problems Dr. Ron Chesser Lecture #17 Conservation, Endangered Species #2...
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