Animal Life Cycles and Reproductive Strategies Flashcards
What two broad reproductive strategies do animals fall under?
K-selection & r-selection
What are K-selection effects?
Large body size, long life expectancy, and production of fewer offspring, usually extensive parental care
What are r-selection effects?
produce many offspring, lower parental care, shorter lifespan
Explain Budding.
Type of Asexual Reproduction; new individuals arise from outgrowths of existing ones
Explain Stony Corals and Hydras Budding.
In stony corals, buds never separate
from parents, forming massive
colonies of clonal individuals. In hydras, the buds separate into new free-living hydras.
Explain Fission
Type of Asexual Reproduction; splitting and separation of a parent organism into two individuals of approximately equal size.
Explain Fragmentation and Regeneration.
Type of Asexual Reproduction; the breaking of the body into several pieces followed by regrowth of lost body parts
ex. starfish
Explain Parthenogenesis.
Type of Asexual Reproduction; an egg is formed but develops without fertilization; occurs in bees, wasps, ants, aphids, and others
Explain Haplodiploidy.
Unique
Haplodiploid sex
determination
shared with other
Hymenoptera.
Why does Parthenogenesis happen?
Among vertebrates, parthenogenesis is a rare response to low
population density.
ex. Female Komodo dragons for instance, will produce eggs asexually if no males are available. This provides a population
a way to survive an
absence of males, but
lowers genetic variability
Explain Hermaphrodism.
Organisms like the barnacle have fully developed male and female sexual organs. This allows any 2 organisms to mate, reducing likelihood of
incompatibility. Both exchange and receive
sperm.
Why does Sex Reversal exist?
Sex reversal may act as an adaptation to ensure
reproduction can still occur if the resident male dies.
Individuals that undergo sex reversal reproduce in both ways over their lives, carrying on a huge amount of their genes.
What are Reproductive Cycles?
Most animals reproduce based on a seasonal cycle.
Cycles are regulated by
hormones
Those are influenced by day length (photoperiod),
temperature, or other
environmental cues.
Cycles like this are
useful because they
conserve resources, allowing reproduction
only when sufficient
resources are availab
What are Dramatic Cycles?
Example: This is a periodical cicada, Magicicada
septemdicem.
They spend 17 years underground as
root-sap feeding nymphs.
They emerge in a massive swarm at
once to mate, lay eggs, and die over a
summer.
Some stray cicadas emerge a year too
early or a year too late.
They will likely not find mates at all.
Timing is critical!
Effect of climate change on reproductive cycles.
Since many reproductive
cycles are tied to climate, warming can negatively impact mating.
