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Ecology & Environmental
Problems
Dr. Ron Chesser
Lecture #17
Conservation, Endangered Species #2
Reading: 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
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Asian clam
Tumbleweed
Pheasant
Insects
Nutria
Hunting/exploitation & Sport
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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
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Factors
Mating success
Birth rates (fertility & fecundity)
Death rates
Variation in population demography
Growth curves in reverse
Conservation Considerations
 Environmental Risk
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Predator – prey relationships
Local endemism and extinction risk
Generalists versus specialists
Mechanisms to withstand environmental
variations
 Hibernation, 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
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Risks
Inbreeding
Reduced Adaptability
Genetics & Behavior
Behavioral Ecology
Related species and genetic identity
Effective Population Size
Spatial heterogeneity
Genetic Characteristics
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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 "outcrossing" 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
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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
disease
To 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).
Red Ruffed Lemur
Black and White Ruffed Lemur
Behavioral Ecology
POLYGYNY (POLYGAMY)
POLYANDRY
PHILOPATRY
FIDELITY
DISPERSAL
SNEAKY BREEDERS (SF)
Habitat Fragmentation
Habitat Fragmentation
Playa Lakes & Fragmentation
Vagility
Volant
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
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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