Summary
Reproductive Animal Strategies - a summary
- Course
- Life Sciences
- Institution
- 12th Grade
Comprehensive summary on reproductive animal strategies for Grade 12 (IEB) students. Typed and in colour. From a student with a >85% average.
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Reproduction = production of = new generation of organisms from = existing generation
↳ a life process that ensures = continued survival of = species
The goal of each animal species:
Ultimate goal = produce max. no. of surviving offspring with least amt. energy
↳ reproductive effort
Asexual reproduction = lower + microscopic animals
↳ energy efficient = low reproductive effort
↳ only involves = single animal
Sexual reproduction = all vertebrates
↳ much more complex
↳ needs much higher energy input = high reproductive effort
Unique reproductive strategies = developed
↳ ensure max. reproductive success in diff. environments
↳ enables species = successfully breed
↳ = survive to reproductive age
Strategy = genetically determined behaviour
Reproductive strategies:
A. Courtship
B. External vs. internal fertilisation
C. Ovipary, ovovivipary & vivipary
D. Amniotic egg
E. Precocial & altricial development
F. Parental care
,A. Courtship
In animals behaviour and/or signals
= designed = attract another animal = for mating + breeding
Simple strategies
Chem. stimuli = pheromones
Visual stimuli = brightly coloured body parts
Auditory stimuli
↳ used = mates = find each other
↳ used singularly/ combination
Females of some insect species = produce = species-specific pheromones
↳ guide males towards them
↳ eg. moths
Most frogs = return to water = mating + breeding
↳ once @ breeding ground = males = sing = attract females
↳ grunt/croak
↳ each species = own song = attract females = of that species
Male birds = advertise when ready to mate = species-specific song = attract female
↳ once meet = male must impress & sexually stimulate female
↳ eg. metallic-green breeding plumage = male Malachite sunbird
extra-long tail feathers = widowbirds
Complex strategies
More elaborate courtship forms = specific to species
Females usually favour males that are:
↳ larger
↳ = more elaborate physical features
↳ display more energy = courtship activity than other males
↳ helps choose better male
↳ reinforce bonding pair (important = parental care)
↳ promises healthier offspring
Certain bird species = complex courtship patterns
↳ eg. Blue Crane’s courtship displays include:
↳ complex + extended series of calls
, ↳ males = elaborate dances
Springbok = annual rut = period of sexual excitement
↳ usually = when animals = peak condition
↳ to attract females = males = defend territories with loud grunts
↳ = attack vegetation with horns
↳ = deposit middens = urine + dung
↳ = ritualised display
↳ most young = born = 6 months later in spring
↳ shortly before = rain season begins
↳ timing ensures:
↳ mothers = good condition
↳ young = born when = enough available food
↳ enable = reach reproductive age
Some bird species = courtship-feeding
↳ eg. male African hoopoes = feed mates insects
↳ allows female = save energy = incubating
↳ = brooding
Maximising reproduction:
Courtship mechanisms = ensure = males + females = find suitable mates
↳ eg. strongest male
Sexual behaviour in courtship = timed = male + female = ready to mate @ same time
Male = energy expenditure
↳ female = conserve energy = for breeding
Due to these factors = more likely = produce = strong healthy offspring
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