Today: Meiosis, producing genetically diverse offspring, and inheritance

1
Today Meiosis, producing genetically diverse
offspring, and inheritance
2
Meiosis producing gametes
For life to exist, the information (genes) must
be passed on.
Mitosis producing more cells
3
Voles

• Prairie
• Monogamous
• Both parents care for young

• Montane
• Nonmonogamous
• Mother cares for young briefly

4
Voles

• Prairie
• Monogamous
• Both parents care for young
• More receptors

• Montane
• Nonmonogamous
• Mother cares for young briefly
• Less receptors

Same levels of oxytocin and vasopressin
5
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

6
haploid
X 23 in humans
X 23 in humans
diploid
X 23 in humans
Sexual Reproduction The combination of genes
inherited from Mom and Dad.
7
Asexual Reproduction
Sexual Reproduction
vs.
extremely low genetic diversity
greater genetic diversity
8
Asexual Reproduction
genetically identical to parent
(this tree can reproduce both sexually and
asexually)
9
Why does sexual reproduction exist?

• Cons
• Need two individuals
• Hard to find mate
• Diseases/Competition

• Pros
• Genetic diversity

10
Screw worm flies
11
F
M
sterile
Sterile male screw worm flies led to decreased
populations because of screw worm monogamy.
12
F
M
sterile
In most other species, because females mate with
multiple males, introduction of sterile males has
little effect.
Sterile male screw worm flies led to decreased
populations because of screw worm monogamy.
F
M
sterile
13
In most other species, because females mate with
multiple males, introduction of sterile males has
little effect.
Hi, want to study biology together?
F
F
M
M
sterile
fertile
14
10-40 of offspring in monogamous bird species
are fathered by an extra-pair male
15

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

16
In mammals, child-rearing is most commonly done
by the female. She provides milk.
17
Less than 0.01 of mammals are monogamous
18
Do Males and Females have different attitudes
toward sex and relationships?
19
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

• Female answers
• Would you go out with me tonight?
• 50 yes

• Male answers
• Would you go out with me tonight?
• 50 yes

20
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

• Female answers
• Would you go out with me tonight?
• 50 yes
• Would you come to my apartment tonight?
• 6 yes

• Male answers
• Would you go out with me tonight?
• 50 yes
• Would you come to my apartment tonight?
• 69 yes

21
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

• 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

• 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

22
Why do Males and Females have different attitudes
toward sex and relationships?
23
The male perspective on monogamy
24
Eggs require large resource input. A clutch of
bird eggs can be 20 of birds weight. Sperm
are cheap.
25
Human Males 250,000,000 sperm/ ejaculation
Human Females 1 egg/month
26
The female reproductive system
27
Sperm competition

• Sperm can survive for several days in a womans
  reproductive tract.
• In Great Britain in a survey of 4,000 women
• 0.5 had sex with 2 different men within 30
  minutes
• 30 within 24 hours

sperm competition.
28
The female reproductive system
29
Female mammals provide additional resources in
form of milk.
30
Mating pairs share genetic information and
possibly help in child-rearing
31
What are the consequences of the different male
and female attitudes toward sex and relationships?
32
Zebra Finch
33
Zebra finch pairs were allowed to mate 9 times
34
Then a new male was brought in and allowed to
mate with the female once.
35
Last male advantage
Original male (mated 9 times) fathered 46 of
offspring
The last male that only mated once fathered 54
of offspring
36
Last male advantage
To ensure fatherhood males mate guard and produce
copious quantities of sperm
37
After successfully mating, male purple martins
call and attract younger males
Purple Martins
38
The older males then cuckold the younger males
females
Younger males with nests near older males only
father 29 of eggs in their nests.
39
Older males produce 4.1 offspring with their mate
and 3.6 by younger neighbors mate.
Younger males with nests near older males only
father 29 of eggs in their nests.
40
Older males produce 4.1 offspring with their mate
and 3.6 by younger neighbors mate.
What advantage is their for females to accept or
solicit EPCs?
41
Gunnisons Prairie Dogs
Sexually monogamous female squirrels have a 92
chance of successfully giving birth.
42
Gunnisons Prairie Dogs
Sexually monogamous female squirrels have a 92
chance of successfully giving birth. Non-monogamo
us females have a 100 chance of giving birth
43
Can females detect compatible genes?
http//www.pbs.org/wgbh/evolution/library/01/6/l_0
16_08.html
44
How can a female know which male has successful
genes?
45
Females may choose traits, like large displays,
that are disadvantageous for male survival.
46
How can females determine good males?
47
Color Bright coloring can be correlated with
health
48
But a male with a mate is judged as being high
quality even if he is less colorful
49
(No Transcript)
50
Voles

• Prairie
• Monogamous
• Both parents care for young
• More receptors

• Montane
• Nonmonogamous
• Mother cares for young briefly
• Less receptors

Same levels of oxytocin and vasopressin
51
(No Transcript)
52
(No Transcript)
53

• Males must choose between having more offspring
  (more mates) or helping to raise fewer offspring
  (sperm do not require many resources)
• Females choose males that can provide good
  genes or resources for offspring
• (eggs, gestation, and/or lactation require high
  resource input)

54
Am I the only one? Am I better off helping with
these kids or should I mate with someone else?
Is this the best I can do? Maybe I can find
someone with better genes or more genetic
diversity.
55
Asexaul Reproduction
Sexaul Reproduction
vs.
extremely low genetic diversity
greater genetic diversity
How does sexual reproduction generate genetic
diversity?