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

RECIPROCAL ALTRUISM

Necessary conditions:1. cost << benefits2. recipient and donor are recognizable3. roles are changed occasionally