Reproductive Stratergies In Animals Flashcards
(19 cards)
Define reproductive strategies:
Reproductive strategies are structural, functional, and behavioral adaptations that increase chances of fertilization.
What are the two main types of reproductive strategies?
- K -strategy
- R -strategy
Explain the K -strategy:
K = carrying capacity -> animals using the K-strategy experience exponential growth, then fluctuate around the carrying capacity.
- Few offspring.
- High level of parental care.
- Offspring have higher chances of survival.
Explain the R -strategy
R = growth rate.
- Lots of offspring.
- No parental care.
- Offspring have a low survival rate.
Define survivorship curve:
A curve that depicts the number of survivors of a particular species at each stage of their life.
Explain type I Curve:
Type I or Type A
- The population’s mortality is low until they near the end of their lifespan.
- K-strategy organisms
Explain the type II curve:
Type II or Type B
- Organisms whose mortality decreases steadily over time (the young are as likely to die as the old)
Explain type III curve:
Type III or Type C
- High mortality rate among the young, but mortality dramatically decreases as they mature.
- R-Type strategists
Define Courtship:
Courtship is the behavioural patterns of males & females that leads to mating and ultimately offspring among animals.
What is the purpose of courtship?
- Ensures both sexes are ready
- Identifying mating partners -> no wasting time and energy.
- Helps with the choice of mating partners.
What are the different courtship stimuli?
- Visual stimuli
- Sound stimuli
- chemical stimuli
- physical movement
Compare internal vs external fertilization:
Internal:
-Insects & terrestrial vertebrates
-Terrestrial habitat
-Fewer gametes
-Protected by shell of female body -> higher chance of survival.
VS
External:
-Fish & Amphibians
-Aquatic Habitat
-Lots of gametes (ova secretes chemicals to attract sperm)
-At risk of environmental changes - lower chance of survival.
Ovipary, Ovovivipary, Vivipary are reproductive strategies that indicate _____??
They are reproductive strategies that indicate where embryo develops and how it receives nutrition:
Explain Ovipary:
- Lay eggs in external environment.
- Fertilization can be internal or external.
- Young develop in egg outside mother’s body.
Example:
- Birds, Frogs, Reptiles, Fish.
Explain Ovovivipary:
- Eggs hatch inside body.
- Internal fertilization.
- Embryo surrounded by thin membranous shell.
- No physical connection between mother & developing embryo.
- Development in an egg in the female is protection.
Example:
- some Sharks, lizards, snakes
Explain Vivipary:
- Internal fertilization.
- Egg develops into embryo.
-Embryo is directly connected to mother & receives nutrients from placenta. - Few gametes produces = low energy
- High parental care = high energy
Examples:
Mammals, some Sharks, scorpions.
What is an Amniotic Egg?
- Egg developed specifically for terrestrial (earth) life.
- The embryo is enclosed in a hard shell
- It has four extraembryonic membranes
- They prevent dehydration & provide nutrients, water, oxygen & remove waste.
Define parental care:
Behavioural patterns where parents exert energy on feeding & protecting their offspring.
Explain Parental care in mammals:
- Most mammals are helpless after birth & completely dependent on parental care.
- Receive milk from their mothers.
- Keep warm off body heat of parents.
- Parents protect them from predators
- Parents have to teach behavioural patterns -> independence.
