Homework 2 due F 2/23

Bonus 1 due W 2/28

Evolution: A species’ genetic component changes as the individuals reproduce. These changes are based on how the DNA changes and who reproduces.

As DNA changes; traits change.

DNA Traits

Natural Selection:Individuals that are most

successful at reproducing will pass on more of their genetic

information.

Reproductive success = evolutionary success

Individuals are selected…

But populations evolve via changes in DNA during reproduction.

CB 24.6

Who evolves?…Species.

•A population that can produce fertile offspring

•A population that does reproduce

**A population sharing genetic information**

A. harrisi A. leucurus

Evolution: A species’ genetic component changes as the individuals reproduce. These changes are based on how the DNA changes and who reproduces.

Meiosis splits apart the pairs of chromosomes.

X 23in humans

haploid

diploid

X 23in humans X 23

in humans

X 23in humans

Inheritance = The interaction between genes inherited from Mom and Dad.

Mitosis only:extremely lowgenetic diversity

Meiosisand Mitosis:greater geneticdiversity

vs.Asexual Reproduction

SexualReproduction

Asexual Reproduction

genetically identical to parent

(this tree can reproduce both sexually and asexually)

Why does sexual reproduction exist?

Cons:

• Need two individuals

• Hard to find mate

• Diseases/Competition

Pros:

• Genetic diversity

VolesPrairie

• Monogamous

• Both parents care for young

Montane

• Nonmonogamous

• Mother cares for young briefly

Why might these voles use different reproductive strategies?

Prairie voles:

Resource poor habitat

• Monogamous

• Both parents care for young

Montane voles:

Resource rich habitat

• Nonmonogamous

• Mother cares for young briefly

byeHow does evolution work for a behaviors such as monogamy?

monogamous non-monogamous

byeHow does evolution work for a behaviors such as monogamy?

monogamous non-monogamous

How does evolution work for a behaviors such as monogamy?

monogamous

non-monogamous

After several generations…

How does monogamy work?

from “The Myth of Monogamy” by Barash and Lipton

Screw worm flies

Sterile male screw worm flies led to decreased populations because of screw worm monogamy.

F M

sterile

Sterile male screw worm flies led to decreased populations because of screw worm monogamy.

In most other species, because females mate with multiple males, introduction of sterile males has little effect.

F

F

M

sterile

M

sterile

In most other species, because females mate with multiple males, introduction of sterile males has little effect.

F M

sterilefertile

FM

Hi, want to study biology together?

Mating pairs share genetic information and possibly help in child-rearing

10-40% of offspring in a socially monogamous bird species are fathered by an extra-pair male

•Social Monogamy = pair lives/works together, but not “faithful”•Sexual Monogamy = pair raise young and only copulate with each other

In mammals, child-rearing is most commonly done by the female. She provides milk.

Less than 0.01% of mammals are monogamous

1.Would you have dinner with a boy/girl you met today?

1.Would you have dinner with a boy/girl you met today?

2.Would you go to a boy’s/girl’s house who you met today?

1.Would you have dinner with a boy/girl you met today?

2.Would you go to a boy’s/girl’s house who you met today?

3.Would you sleep with a boy/girl who you met today?

Do Males and Females have different attitudes toward sex and relationships?

On a college campus an attractive male or female asked the opposite sex: “I have been noticing you

around campus. I find you very attractive…”

Male answers:…Would you go out

with me tonight?= 50% yes

Female answers:…Would you go out

with me tonight?= 50% yes

On a college campus an attractive male or female asked the opposite sex: “I have been noticing you

around campus. I find you very attractive…”

Male answers:…Would you go out

with me tonight?= 50% yes…Would you come to

my apartment tonight?

= 69% yes

Female answers:…Would you go out

with me tonight?= 50% yes…Would you come to

my apartment tonight?

= 6% yes

On a college campus an attractive male or female asked the opposite sex: “I have been noticing you

around campus. I find you very attractive…”

Male answers:…Would you go out

with me tonight?= 50% yes…Would you come to

my apartment tonight?= 69% yes…Would you go to bed

with me tonight?= 75% yes

Female answers:…Would you go out

with me tonight?= 50% yes…Would you come to

my apartment tonight?= 6% yes…Would you go to bed

with me tonight?= 0% yes

Why do Males and Females have different attitudes toward sex and relationships?

The male perspective on monogamy

Eggs require large resource input.

A clutch of bird eggs can be ~20% of bird’s weight.

Sperm are cheap.

Human Females:~1 egg/month

Human Males:250,000,000 sperm/ ejaculation

Mating pairs share genetic information and possibly help in child-rearing

What are the consequences of the different male and female attitudes toward sex and relationships?