Download 06_prughNS

2 WORK-STUDY JOBS
1. Endangered species and biodiversity
Duties: - collect data on endangered species traits
- enter data into Access database
2. Plant-insect ecology
Duties: - survey seedheads for bio control insects
- enter data into Excel spreadsheet
spotted knapweed
Qualifications:
majoring in Biology
interest in conservation
good work ethic
good computer skills
To apply: www.students.ubc.ca/workstudy
Project # 1235
Centaurea maculosa
REVIEW QUESTION
# children
Education level
♦ Women with more education have fewer
children
♦ Should society become dumber over time???
FITNESS
The relative reproductive success of a gene in the
long term
variant of a gene: allele
e.g., eye color:
SELECTION VS. EVOLUTION
Selection is a process
Selective agents (weather events, predators,
competitors) favor one form of a trait over another
(larger beaks, longer legs, stronger horns)
Evolution is an outcome
Change in allele frequencies in the population
GENETIC DRIFT
Random changes in the frequency of alleles from
generation to generation
Equivalent to sampling error
2 main effects:
1. Changes allele frequencies
2. Decreases genetic variation
GENETIC DRIFT
Small populations can lose genetic varation
because of drift
Bottleneck: population crash causes loss
of alleles
GENETIC DRIFT
Example: the cheetah (Acinonyx jubatus)
Fastest land mammal: 110 kph
Went through severe genetic bottleneck 10,000
years ago: lost nearly all variation
GENETIC DRIFT
Founder effect: a few individuals colonize a new
area
New population has different allele frequencies (and
less diversity) because of “sampling error”
Example: Amish in Pennsylvania
- descended from 200 Germans
- commonly have Ellis-van Creveld syndrome
- inbreeding makes impact of bottlenecks and
founder effect worse
INCLUSIVE FITNESS
½
½
+
½ =1+
¼
+
¼
= 1.5
KIN SELECTION: traits that
increase inclusive fitness are favored
INCLUSIVE FITNESS
Relative reproductive success of a gene in an individual
plus its close relatives
Ex., you have the “helpful” gene
“helpful” gene will spread if:
rxb>c
r = relatedness
b = benefit
c = cost
Hamilton’s rule
KIN SELECTION
Classic case: Eusocial insects
Eusocial animals have sterile worker caste
- Evolved 11 times in Hymenoptera
- Also termites, crustaceans, 1
mammal (naked mole rat)
How could this evolve?
Haplodiploidy:
are haploid (unfertilized)
are diploid (fertilized)
= ¾ genes shared
More related to sisters than own offspring!
ALTRUISM
What if r = 0?
rxb >c
0
Reciprocal altruism: helping another
individual in expectation of receiving
help in the future
Robert Trivers (1971)
RECIPROCAL ALTRUISM
Vampire Bats
3 species in central and south America
Live in large groups, often unrelated to bats
around them
If no meal, may die
within 24 hours
Bats will often regurgitate
blood to hungry neighbors
RECIPROCAL ALTRUISM
Necessary conditions:
1. cost << benefits
2. recipient and donor are recognizable
3. roles are changed occasionally