Grade 12 Reproductive Animal Strategies Flashcards
What is the goal of each species?
Produce maximum number of surviving offspring while using the least amount of energy
Define Courtship
Behaviours designed to attract another animal for mating and breeding
List the three types of simple strategies
Chemical (pheromones)
Visual (bright colours)
Auditory
How does courtship maximise reproduction?
- Ensure males and females find suitable mates
- Sexual behaviour timed so male and female are ready for mating
- Energy expenditure generally by male, so female conserves energy for breeding
Where does external fertilisation take place and in what type of species does it occur?
Takes place in water
Occurs in most aquatic vertebrates
How is the uncertainty of external fertilisation overcome
Large numbers of sperm and eggs are released
In what type of species does internal fertilisation usually occur?
Terrestrial Vertebrates
How does internal fertilisation maximise reproduction?
Gametes closer together
Reduced gamete production saves energy
Define Ovipary
Eggs develop outside of the parent
What is a downside of Ovipary in aquatic creatures, and how is it offset?
High energy input from female for egg production
Offset by less energy being needed for yolk production and parental care
Define Ovovivipary
Internally fertilised eggs are kept inside the female until they hatch
What type of fish is Ovovivipary common in?
Surprisingly common amongst sharks
Does the embryo of an Ovoviviparous species rely on its mother?
No, food comes from yolk of egg.
Only dependent on mother for physical protection
How does Ovovivipary maximise reproduction?
Fewer eggs produced, so lower energy expenditure
Developing embryo less vulnerable
Young are fully developed, so can get their own food
Define Vivipary
Fertilisation is internal and the eggs do not have a shell
How does the embryo of a Viviparous species obtain nourishment?
Obtained continuously from the mother, usually through a placenta
What major evolutionary innovation allowed the first reptiles to colonise dry land?
The Amniotic Egg
How does the amniotic egg maximise reproductive success?
Fluid-filled Amnion protects embryo against dehydration
Allantois is a reservoir for nitrogenous waste in reptiles & birds
Yolk Sac holds nutritious food
Chorion surrounds other membranes
Define Precocial development
Born almost fully developed.
Where does energy expenditure go to for Precocial development?
Pre-natal developments
List four defining traits of Precocial Species
Are born with;
1. Open eyes and have hair or down
2. Large brains relative to body size
3. Are immediately active
4. Are not confined to nests
How does Precocial development maximise reproduction?
Offspring can find own food and look after themselves
Why do many herd animals develop precocially?
Allows the young to keep up with the movement of the herd, which is useful when movement to not overuse a food source is important.
Define Altricial development
Born not well-developed
List five defining traits of Altricial Species
Often naked
Cannot walk or fly
Eyes often closed
Rely on parents for warmth, transport, & food
Require care and protection for a long time
How does Altricial development maximise reproduction?
Parental care protects the young after birth
Offspring reach reproductive age quickly due to being easier to feed and growing more rapidly
Safer from predation
Give four examples/general groupings of Altricial Species
Small mammals
Humans
Tree-nesting birds
Marsupials
Define parental care
Pattern of behaviour in which the parent spends time or energy to improve survival, condition, and future reproductive success of offspring
What advantage does parental care provide?
Fewer young need to be produced for the same amount to survive
What are the two types of Parental Care?
Pre-Natal Care (e.g., Guarding eggs, building nests, placental nourishing)
Post-Natal Care (e.g., Providing food, protecting offspring, teaching offspring)
Why is parental care so important in mammals
Most young mammals are completely helpless
Give the typical traits of K-strategy species
Produce only a few offspring
High level of parental care and whole group takes care of offspring
Most babies born reach adulthood
Tend to be a climax species
Give typical traits of R-strategy species
Sexually mature at late age
Produce large number of eggs
Only a few offspring reach adulthood
