Day 16 October 30th Chapter 9Mating Systems

Dr. Amy B HollingsworthNatural Science Biology

Fall 2014

9.14 Monogamy versus polygamy: mating patterns can vary across human and animal cultures.

Mating Systems

Polygamy• When some individuals attract multiple

mates while other individuals attract none

Monogamy • Most individuals mate and remain with

just one other individual

Mating Systems

Polygamy subdivided into:

Polygyny • Individual males mate with multiple

females

Polyandry• Individual females mate with multiple

males

Mating Systems Are Not Easy to Define

Three issues complicate the task:

1. Differences between animals’mating behavior and bonding behavior

2. Mating system variation within the species3. Males and females vary in their mating

behavior

Pair bond—appears monogamous

Examination of Birds and Mammals Reveals One Sharp Split

Are humans monogamous or polygamous?

9.15 Sexual dimorphism is an indicator of population mating behavior.

Body Size Is an Important Clue to Behavior.

Level of competition among the individuals of each sex

Selection for larger and larger body size when competition is high

It’s almost impossible to distinguish males from females among most bird species.

Why does that mean they are monogamous?

Men are bigger than women.

What does that tell us about our evolutionary history of monogamy

versus polygamy?

9.16–9.17

Communication

and the design of

signals evolve.

Chemical Communication in Animals

Communication

An action or signal on the part of one organism that alters the behavior of another organism

What types of animal behavior require communication?

What types of communication do animals use?

Types of Animal Communication

Chemical Acoustical Visual

Complex Forms of Communication

Honeybee waggle dance

What is language?

How is language identified?

Vervet monkeys

American Sign Language taught to chimpanzees and gorillas

Human language

9.17 Honest signals reduce deception.

Conveying accurate information

Honest Signal

Cannot be faked

Given when both the individual making the signal and the individual responding to it have the same interests

Carries the most accurate information about an individual or situation

Deception evolves!

“Begging” allele

Evolutionary “arms race”• Unambiguous signals• Sophisticated patterns of deception

An organism’s phenotype includes its behaviors.