Post on 18-Dec-2015
2 WORK-STUDY JOBS1. 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
Qualifications: majoring in Biologyinterest in conservationgood work ethicgood computer skills
To apply: www.students.ubc.ca/workstudyProject # 1235
spotted knapweedCentaurea maculosa
REVIEW QUESTION
♦ Women with more education have fewer children
♦ Should society become dumber over time???
# children
Education level
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
Evolution is an outcome
Selective agents (weather events, predators, competitors) favor one form of a trait over another (larger beaks, longer legs, stronger horns)
Change in allele frequencies in the population
GENETIC DRIFTRandom changes in the frequency of alleles from generation to generation
Equivalent to sampling error
2. Decreases genetic variation1. Changes allele frequencies
2 main effects:
GENETIC DRIFTSmall populations can lose genetic varation because of drift
Bottleneck: population crash causes loss of alleles
GENETIC DRIFTExample: the cheetah (Acinonyx jubatus)
Went through severe genetic bottleneck 10,000 years ago: lost nearly all variation
Fastest land mammal: 110 kph
GENETIC DRIFTFounder 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 ¼ ¼ + = 1 + + = 1.5
KIN SELECTION: traits thatincrease inclusive fitness are favored
½
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:
r = relatednessb = benefitc = cost
Hamilton’s ruler x b > c
KIN SELECTION
Classic case: Eusocial insects
Eusocial animals have sterile worker caste
How could this evolve?
Haplodiploidy: are haploid (unfertilized)are diploid (fertilized)
= ¾ genes shared
More related to sisters than own offspring!
- Evolved 11 times in Hymenoptera- Also termites, crustaceans, 1
mammal (naked mole rat)
ALTRUISM
What if r = 0?
Reciprocal altruism: helping another individual in expectation of receiving help in the future
> cr x b
Robert Trivers (1971)
0
RECIPROCAL ALTRUISMVampire Bats
3 species in central and south America
Live in large groups, often unrelated to bats around them
Bats will often regurgitate blood to hungry neighbors
If no meal, may die within 24 hours