exam prep Flashcards
What are the pros of asexual reproduction?
• Pros:
o removes requirement to locate a mate
• searching for mates takes time and energy
• low encounter rates in particular habitats (e.g. parasites)
o facilitates rapid reproduction
• lots of offspring quickly
o perpetuates successful genotypes
• sexual reproduction produces unique genetic combinations
What is the difference of genotype sex-determination and environment sex-determination?
Sex determination: Vertebrates
• genotypic sex-determination (GSD)
o sex chromosomes (e.g. XX/XY, ZZ/ZW)
o all birds & mammals, most fish, amphibians & reptiles
• environmental sex-determination (ESD)
o e.g. temperature
o some fish & amphibians, common in reptiles
What is the cost of sexual reproduction?
• widespread in animals despite its numerous costs
• recombination breaks up successful gene combinations
o crossing over during meiosis
o but produces offspring with novel genotypes
• Costs of mating:
o gamete production (energetically expensive)
o intrasexual selection (competition in order to select mate)
o intersexual selection
o locating a mate
o mate choice (not all individuals reproduce)
o parental care: costly & not always successful
o sexually transmitted diseases
What are the life history strategies?
Life history strategies:
• r/K selection theory
o method to describe/categorise life histories
o It is on a spectrum
• r-selected animals
o production of a large number of offspring (of whom only a minority may survive) as early in life as possible
o live fast, die young
• K-selected animals
o production of a smaller number of ‘fitter’ offspring with higher chances of survival
what are the difference between r and k selection?
• r-selected animals
o production of a large number of offspring (of whom only a minority may survive) as early in life as possible
o live fast, die young
• K-selected animals
o production of a smaller number of ‘fitter’ offspring with higher chances of survival
Difference between Marine and terrestrial environment:
Marine is stable and predictable, while terrestrial is not plus need support structures in terrestrial
Difference between internal and external fertilisation with life history?
Internal fertilisation reduces the amount of offspring the female can produce and direct development occurs
What is the life history of Field crickets?
• male display behaviour related to mating success • display behaviour costly o energy, predator detection • high display rates = high quality male • field crickets (Teleogryllus commodus)- Orthoptera o protein diets (low, medium, high) o adult females, nymphs • high protein → longer lifespan o adult males • high protein → shorter lifespan o Females respond to males that call more o protein level • influence resource allocation o high protein: ↑ calling effort • decreased body condition o higher reproductive success o but ↓ life span o life history trade-off
What is the life history of Perrodical Cicadas?
• Hemiptera
• life cycle
o larvae: underground, feed on tree roots
o adults: winged, dispersal, reproduction
o long-lived larvae, short-lived adult
o semelparous
• Magicicada: eastern US
o long life cycle
o prime number life cycles
• 13 years
• 17 years
o predators unable to ‘track’ and get their reproductive cycles synched with the cicadas
o synchronised emergence
• huge numbers
• predator satiation
• among species in area
o Magicicada: species complex
• 3 ecologically & morphologically distinct species
• each has 13 year & 17 year forms
• ancestral form: 13 year (+ 4 year life cycle extension)
• 17 year form: favoured in cold conditions (I-XVII)
• 13 year form: favoured in warm conditions (XVIII-XXX)
• broods emerge in different years
cannot interbreed (temporal reproductive isolation)
• life cycle switch in one species pair
17 year form reverted to 13 year cycle
emerge in same year as 13 year form mtDNA
Name the different types of parasites?
• ectoparasite
o live on the outer surface of the host
o e.g. skin, hair
o attachment structures (hooks, suckers, teeth)
• endoparasite
o live inside the host’s body
o e.g. intestines, lungs, liver, muscles, internal organs, blood
• parasitoid
o insects whose larvae develop by feeding upon the bodies of other
o arthropods (usually insects), resulting in the death of the host
o Hymenoptera (wasps), Diptera (flies)
o intermediate between parasites and predators
o hyperparasitoids: parasitoids of parasitoids
Describe parasites Life History evolution?
• life cycles
o sexual reproduction, direct development, single host
o sexual/asexual reproduction, series of life stages, multiple hosts
o asexual reproduction of immature life stages
o high incidence of hermaphrodites
• morphology
o different to free-living relatives
• enhance transmission
o reproductive output
• life history co-evolves with host
o body size smaller than host
o body size correlated with most life history traits (e.g. fecundity)
o thermal environment
o less constrained in ectoparasites
Benefits of the Amniotic egg?
• Amniotes
o facilitates life on land (no free living larval stage)
o protective calcareous shell (permeable)
o yolk nourish embryo
o Still live in aquatic environment but does not dry out
o three embryonic membranes
• allantois: store embryo waste
• chorion: blood vessels, gas exchange
• amnion: fluid-filled, protects embryo
Fish and amphibian’s r/k strategy?
• Fishes & amphibians
o reproduce in aquatic environments
o fish: can adopt strategies similar to marine invertebrates
o trend towards r-selection, but cover entire spectrum
Reptiles, birds and mammals r/k strategy?
o internal fertilisation, amniotic egg
o trend towards K-selection
o ↑ provisioning & parental investment, egg size, body size & life span
o sociality: overlapping generations, delayed maturity, parental care
Fertilisation for aquatic vertebrates?
• external fertilisation o aquatic vertebrates o most fishes & amphibians • Agnathans (jawless fishes) o ova & sperm released into coelom o shed through genital pores
Fertilisation for terrestrial vertebrates?
• all other vertebrates
o duct systems carry ova or sperm
o reproductive function
• internal fertilisation
o terrestrial vertebrates: reptiles, birds & mammals
o some fishes (e.g. sharks) & amphibians (salamanders, caecilians)
• often have intromittent organ
o birds press cloaca’s together (except ratites, ducks & geese) some amphibians
o squamate reptiles & tuatara: hemipenes
o turtles & crocodiles: penis
o mammals: variable penis structure
• many marsupials: bifid penes (two-headed)
• most mammals: bone support (bacula)
• blood-filled tissues (primates, horses, rabbits)
• spermatophores (sperm packets)
o deposit on substrate
o females uptake spermatophores with cloaca
o Sperm storage
o Internal fertilisation
What are the 3 ways amphibians fertilise?
• majority of Anurans (frogs & toads) o external fertilisation o no intromittent organ • most Caudata (salamanders & newts) o internal fertilisation o no intromittent organ • Gymnophiona (caecilians) o internal fertilisation o intromittent organ
Aquatic vs Terrestrial Environments?
• physical properties of water (vs air)
o 1000x more dense (provides support)
o 50x more viscous (impedes locomotion)
o 3000x thermal capacity (relatively stable temperatures)
o sound travels 4-5x faster (communication)
o impedes vision (can see further on land)
o 30x less oxygen content
o lower water loss (desiccation a major challenge on land)
• aquatic environment
o external fertilisation, r-selected strategies
what is Chinook Salmon Life History?
• largest salmon species (adult size 18-61 kg)
• arctic, northwest & northeast Pacific
• life cycle (life span 4-8 years)
o anadromous: adults live in ocean, breed in freshwater
o adults: ~3-6 years at sea, return to natal river to spawn
o mate & lay eggs (3000-14000) in nest pocket (redd) guard eggs for up to 1 month, then die (semelparous)
o eggs 3-5 months to hatch
o fry/parr: up to 2 years in freshwater before moving to estuary/ocean
Life History of Evolution in Reptiles?
• terrestrial ectotherms o low metabolic rate (↓ energy needs) o behavioural control of body temperature • influence life history evolution • life history traits differ from endothermic vertebrates o smaller offspring size o larger litter sizes o lower growth rate o infrequent reproduction
What is the Life History evolution in Birds?
• oviparous
o variation in egg size
• eggs laid in nest
o one or both parents incubate eggs
• hatchlings
o altricial: naked, need warmth & food until leave nest
o precocial: well-developed, leave nest once dry
• reach adult body size when fledge (determinate growth)
• stay with parents until reach independence
• sexual maturity & breed
o continue to breed until die
Why Do Lizards Shed Their Tails?
- escape predator’s grasp
- tail distracts predator
- make a getaway
- last-ditch strategy
- caudal autotomy
- Why:
- direct the predator’s attack towards the tail (expendable)
- rarely survive attacks directed to the head or body
What gives us the most energy?
- Nectar
- Muscle
- Sticks
- Grass
- Soil
- (^^ in order)
What are the types of guts?
What are the types of guts? • Simple sac-like gut o Single opening – 2-way flow o e.g. flatworms • Tube-like gut o Two openings, mouth and anus – 1-way flow o Allows specialisation of gut regions o Allows food storage o Allows for large food to be digestive o Allows for specialisation o Larger food are complex thus need segmentation of digestive tract
How do sponges feed?
Filter feeder
How do Cnidarians feed?
o 2-way sac-like gut
o Intracellular and extracellular digestion
o Use of nematocyst (like a harpoon) which have poison on it, reducing the preys ability to escape.
How do flatworms feed?
o 2-way sac-like gut
o Pharynx is situated on the middle of the body
o Uses pharynx and muscle body to capture prey
o Wrap around prey or entangle in slime
o Food swallowed whole or in pieces
o Digestion is first extracellular, then engulfe
How do annelids feed?
o True coelom o 1-way gut o Very wide range of feeding styles • Suspension • Deposit In-Direct deposit feeders • Non-selective • Ingest sediment and assimilate organic material • Very low organic matter content (1-2%) • Eat soil Direct deposit feeders • Selective • Select food using tentacles
How do molluscs feed?
o Radula • Ribbon of chitinous teeth • Project radula out of mouth • Radula moves like conveyor belt • over odontophore • Teeth scrape surface
