Lecture 7. Animal Diversity: Reproductive Strategies Flashcards
What is the purpose of reproduction ?
- Increase fitness
2. Get as many genes as possible into the next generation
What are the various challenges animals face when reproducing ?
- Choosing and finding a mate
- Ensuring fertilisation success
- Ensuring offspring survives to reproduce
What are the two types of interactions ?
- Intraspecific
2. Interspecific
What are intraspecific interactions ?
Interactions within species
What are some examples of intraspecific interactions ?
- Group living
- Competition
- Reproduction
- Sexual conflict
What are interspecific interactions ?
Interactions between species
What are some examples of interspecific species ?
- Predation and herbivory
- Competition
- Mutualism
- Parasitism and disease
- Pollination
What is an example of external fertilisation ?
Marine species releasing sperm and eggs into the water
What is the advantage of external fertilisation ?
- Mass spawning
- Energetically cheap
- Many offspring
- Overwhelms predators
What is the disadvantage of external fertilisation ?
No mate choice
What are the different types of mate systems ?
- Monogamy
- Polygyny
- Polyandry
- Promiscuity
What is monogamy ?
One male one female
What is polygyny ?
One male, multiple females
What is polyandry ?
One female, multiple males
What is promiscuity ?
Multiple males and multiple females
What is sexual selection a form of ?
Natural selection
What do traits selected in natural selection influence ?
Survival
What do traits selected for in natural selection influence ?
Mating success
What is intersexual selection ?
Selection for traits that increase attractiveness to females
What do birds of paradise display ?
Their brightly coloured feathers
How do manikin birds attract mates ?
Perform a dance
How do bowerbirds attract a female ?
Build bowers
What is intrasexual selection ?
Selection for traits that increase success in fighting
What do mates use in intrasexual selection and why ?
Ornaments to indicate their strength this reduces the need for costly unnecessary battles
How did male choice evolve ?
- Good gene hypothesis
2. Sexy sons hypothesis
What is the good genes hypothesis ?
Traits used in display and are energetically costly so give the female an honest signal about how good the males is at acquiring food or resisting disease.
What is the sexy sons hypothesis ?
Traits used to fight or display will be passed on to the females sons, increasing their likelihood of mating in the future
What can sexual selection drive ?
Speciation
How does one ensure fertilisation ?
Get the sperm as close to the egg as possible often using an intromittent organ
How does fertilisation in a cephalopds ?
Hectocotylus - one of the male arms has different tissues which allows it to become rigid with grooves down its arm. This arm then enters the female through a hole in its mantle
What is the intromittent organ called in squamates ?
Hemipene
What are some mechanisms that males have to ensure their sperm fertilises the female ?
- Male guarding
2. Remove sperm of other males
How do males damselflies ensure their sperm reaches the female ?
Wheel position
How do male lovebugs ensure their sperm reaches the female ?
Copulate for several days
How do golden orb web spiders ensure their sperm reaches the female ?
The copulatory palp breaks off during mating acting as a post copulatory plug
How do females invest more energy in offspring than males ?
- Eggs are bigger than sperm
- Incubating eggs
- Internal development of sperm
- Parental care
- Producing milk
How do males maximise their fitness ?
Have as many offspring as possible and hope some survive
How do females maximise their fitness ?
To have few, high quality offspring which survive
What do drosophila so to prevent intersexual conflict ?
Use chemicals that kill the sperm of other males. But this may also damage the female
How do bed bugs combat intersexual conflict ?
The males have needle like structures for traumatic insemination
How do birds usually reproduce ?
Cloacal kiss
What is interesting about the birds penis /
- Usually inverted inside the male
- Rapid eversion during mating
- Anticlockwise spiral
What does more male-male competition result in ?
Longer duck penis
What is interesting about duck vaginas ?
- They are clockwise spiral shaped
- When the female want to mate it relaxes its vagina so it straightens resulting in fertilisation
- In unwanted mating attempts the vagina remains spiraled and sperm very rarely reach the egg
