Ch. 6 Living in Groups
Benefits to living in groups
o Anitpredator- benefits to individuals living in groups.
If someone else is around predator it may get them instead of them then you.
Better at f
Evolution of parental
Interrelated conflicts inherent
in parental care
Patterns of parental care
Most fish lack care.
Testing hypotheses about parental care:
Sex-related investment by parents in offspring
Parental investment in sons
and daughters: Sex allocation
Chromosomal, temperature-dependent (and other environmental determinants;
e.g. p. 284), haplodiploidy
Achemon Sphinx Moth
Achemon Sphinx Moths are members of the hawkmoth family. They are
large, strong and fast. This species is nocturnal and can .
Banded Tiger Moth
Though each species of Tiger Moth has its own pattern, it can be hard to
see the difference
Sex Allocation in the Red Deer
Chloe Bland, Becca Davis, Bekah Honce
4 November 2015
Clutton-Brock, 1986: Dominance, breeding success and offspring sex ratios in red deer
1. What are the major hypotheses of the study?
Superior mothers will produce more so
Male-female conflicts over care, sibling rivalry and parentoffspring conflict
Parental care games: Modeling
which sex cares
W > w because caring females have fewer
resources for eggs
Negotiating level of care
Response to playback: Why
1. What are the hypothesis for both papers? Were there any predictions made?
2. What was the major findings of the papers?
3. Did the results support the hypothesis?
Fast lizard sire more offspring (Jerry 2007)
1. List the dependent variables tested in th
Eberle & Kappeler 2006
1. Explain the differences in the causes and consequences of helping in singular breeders and cooperative
2. Name the 6 hypotheses regarding why species form groups (see introduction). Which ones do the
Aukema and Raffa
3. What effect do predators have on the population aggregation of bark beetles?
The predators pose a pressure on the beetles to aggregate in larger groups This aggregation of
the beetles creates a dilution effect for the group, so e
1. Describe courtship in grebes and albatross. What might courtship components signal to potential
partners? How would you test one of your ideas? They copy each others movements, dance
across the water (shows fitness of the birds), and give gifts/courtsh
Parental investment in sons and daughters
o Sex-determining techniques
Temperature-dependent (and other environmental determinants, p. 248)
Haplodiploidy- all unfertilized become males and all fertilized become femal
Selected studies from text
Intersexual selection: Female
choice in widowbirds & sedge
How do these studies demonstrate female
Besides focusing on different characters, how
was the design of these experiments differ
Biol 320/Fall 2015
Discussion questions: Sex allocation, chapter 10
1. Explain the reasoning behind Fishers theory of equal investment.
If everything else is equal, a 1:1 sex ratio will be favored by natural selection. If the sex ratio is perturbed from 1
Alternative mating tactics in male and female horseshoe crabs
1. Summarize the main results of each paper and relate these to the hypotheses under consideration.
Evaluate the level of support for each hypothesisis it strongly or weakly supported?
Mate choice for genetic benefits
Testing Hamilton and Zuks
The Hamilton-Zuk Hypothesis
Importance of parasites
Host-parasite interactions and
Brightness as a signal of ability to resist
ESS- when it is rare in a population it will increase, when common it will resist invasion
o Male cares/female deserts
WP0>wP1, the benefits of the female desert is greater than the benefit if she
stays and cares.
P1>P0, the benefit of staying
Sexual conflict over mating and coevolution
Appears to be a coevolution between males ability to grasp females and females morphology
that can resist the male.
Males secrete protein in seminal fluid that causes females more likely to die sooner (High
Evolution of parental care
Examples of parental care
o Both males and females caring for the offspring in birds
o Fish, some snakes- care/guard for offspring but do not feed them
What will limit the selfishness of siblings?
o (Full siblings share half of