5 Competition Notes PDF

5 Competition 23 Friday, 3 November 2023 5 Compe((… 14:42 One species prevents another from occupying niche, by being sup Competitive exclusion - prevents a species from occupyin Character displacement - driven by similar mechanism, b behaviour of another due to resource use/allocation. E...

5 Competition 23 Friday, 3 November 2023 5 Compe((… 14:42 One species prevents another from occupying niche, by being sup Competitive exclusion - prevents a species from occupyin Character displacement - driven by similar mechanism, b behaviour of another due to resource use/allocation. Exploitation - species act via the resource e.g., stealing fo perior. ng a niche in real time but is where One species will influence ood etc Exploitation - species act via the resource e.g., stealing fo and no aggression ( interference ) Trait useful is useful at doing certain things Birds eating seeds Distribution of resources in seeds size - not lots huge and s Finch that utilising the resource that has trait that allow Useful only at certain range of sizes. Beak of finch useful at this seed size but not good at oth K curve - expected density/distribution of trait sizes in animals due Here example is expected distribution of trait size of beak size in p How many of a certain trait in certain population How much of trait to we plan to see ood etc small but many at average size ws exploitation of resource, her sizes. e to resource allocation population How many of a certain trait in certain population How much of trait to we plan to see 1:1 relationship - bird with certain beak size useful at certain seed Positive evolutionary response to resources, they become better Assumptions of basic model of utilisation First assumption seeing its not true - not 1:1 ratio Handling time increases with seed size exponentially. So best to ea d size r at using resources available to them. at smaller seeds Handling time increases with seed size exponentially. So best to ea Best value seen here in different sparrows White crown sparrow, better withs smaller beak than all other bird Says here white crown sparrow with bigger beak, doing better. May not be a 1:1 ratio of trait size and resource Individuals better at surviving on abundant species and not rar Positive evolutionary response to resources at smaller seeds ds re fungal species generally Character displacement is the term used to describe an when two similar species inhabit the same E.g., darwins finches Positive evolutionary relationship Distribution of beak sizes due to seed size distribution on the islan The beak size matches seed size. evolutionary change that occurs e environment. nds. The beak size matches seed size. More than one species. How trait changes in relation to trade offs with other species Strong competition in middle and less competition in extreme tr more favourable. If the peaks are two species, you expect to see on left peak, the le selected and on the right side peak, the right side extreme traits b Overtime the distribution of characters separate out along Can get convergence, where species come together closer for comp changeable or substitutional resource. raits. Hence extreme traits eft side extreme traits being being selected for. resource utilisation axis. petition of single non Can get convergence, where species come together closer for comp changeable or substitutional resource. centre of resource distribution is irreplaceable, e.g., a middle size Where these two peaks actually get closer together. allopatric species or populations are those that do not have overlapping geographic ranges Allopatry - things living apart Sympatry - things living together an evolutionary change that occurs w inhabit the same environment. Two species live in allopatry normally, then when come into sym trait which may be compete for same resource as species b. expe trait amongst two species petition of single non e seed which is very important. c Sympatry is the term used to describe populations, varieties, or species that occur in the same place at the same time. when two similar species mpatry, changes trait value of a certain ect character displacement to diverge Two species live in allopatry normally, then when come into sym trait which may be compete for same resource as species b. expe trait amongst two species Character displacement arises when individuals most d reproductive phenotypes of another species are more reproduction than other members of their population Is it going on in nature Example 1 - looks like character displacement but wasn't Correlation between size of snail ( shell length ) and food size d In allopatry, certain snail sizes are observed In sympatric snails, bigger snails get removed in one speci And in another the snails get bigger Turns out ulvae is better competitor than ventrosa so grow rather than its own species. More like competitive exclusio mpatry, changes trait value of a certain ect character displacement to diverge dissimilar from the average resource-use or e successful at acquiring resources or n. does occur ies ws bigger when in Prescence of ventrosa on Turns out ulvae is better competitor than ventrosa so grow rather than its own species. More like competitive exclusio Example where In allopatry they have similar size beaks, but when overlapping in beaks But when given whole data set ( not seen ), we see both species fi with character displacement In sympatry one of the birds lose their black stripe This loss of characteristic studied in these two birds ws bigger when in Prescence of ventrosa on sympatry they have different sized ind it hard to find food and isnt to do This loss of characteristic studied in these two birds The birds look different when they exist in sympatry, wher like the female - and is now brown and white. Gives extenuation of features when animals occur in sympa Easy to discriminate males in sympatric locations, Hard to discriminate when they are in allopatric lo Competing for mates here not food Criteria for character displacement re the male of fly catcher then evolves to look atry , when they are different from each other ocationms when they look similar Hard to actually show they are competing Here is the number of cases that they could prove at each c Its hard to show species are competing criteria level and see, Lake in Canada, inhabited by stickle backs Vancouver island, studies done in these lakes near here. Allows to grab plankton out the water These lakes are only place with Stickleback in First fish to have genome sequenced. Difference between two ecotypes; benthic and limnetic Co-exist in lakes Bethnic live on bottom shallow water eat invertebrates Limnetic feed on plankton and live in open water Difference in morphology as seen; Benthic smaller eye, less bony back, limentic has more bony pl Gills have bony arch and have gill filaments to absorb ox Limnetic have large gill rakers compared to bethnic, to h water Sympatric as they breed together in same small waters and lake is Breed along side in shallow water, so they are sympatric, some se Bethnic live on bottom shallow water eat invertebrates Limnetic feed on plankton and live in open water lates xygen, help take up plankton and grab them out the small so its considered symaptric. eparation but as lakes are small, Breed along side in shallow water, so they are sympatric, some se still together. Certain lineages show this explosive evolutionary diversificatio Stickle back good example Shows adaptive radiation, good example of it in early stages Given rise to many variants in fresh water Bigger differences than Galapagos finches ( Darwin's eparation but as lakes are small, on finches ) An organism where character displacement has been well doc Grow fish in lab and put them in cages in different areas of Breed then cage in the lake, in shallow ( benthic habitat ) or Look at growth rates Trade offs of where they are good at living together Limnetic fish grow best in open water and not in littoral zone an seen ) Character displacement in these gill rakers Comparing gill raker length when both species exist and when n cumented lakes. r open water ( limnetic habitat ) nd vice versa for bethnic ( tradfe off neither do Comparing gill raker length when both species exist and when n When the two species occur together, there is separation of gill character displacement Solitary = middle distributiin of gill raker len Together = divergence of gill raker length Show that there is competition in species As well as gill rakers change, elements of the arm Grow better or worse in different combinations of specie Armour changes - principle componten, measruing dif armour length of spines etc Separation of armour level, limnetic stickleback being neither do raker length - suggesting ngth mour does also. es present etc fferent things that make up armour e.g depth of g more armoured Armour changes - principle componten, measruing dif armour length of spines etc Separation of armour level, limnetic stickleback being A cross made between limnetic and bethnic and put in p 4 treatment pond - Added predation - troat and saw effe 4 control ponds - just normal no predator Predation causes selection on first dorsal spine but not pel fferent things that make up armour e.g depth of g more armoured ponds ects of armour on dorsal and pelvic spine. lvic spine Change in dorsal spine and change in pelvic spine Msx2a, dorsal spine gene seems to increase in frequency whe Pitx1 doesn’t seem to change between ponds Predation causing something that look like character displacem Three common species of finch, Pattern that shows character displacement at community level Finches are a reoccurring study system - here lack 1947 ere predators are present. ment Pattern that shows character displacement at community level Finches are a reoccurring study system - here lack 1947 Documented beak size across different islands Three common species; fortis, firginosa, maginotrisis Pattern of character displacement of different beak sizes Variation between g.fortis, big and small billed. Post drought in 1970's G,magnirostirs has huge beak Beak size change, drought makes beak size small and large. First drought increases size, second reduced it. Change in size of evolution, direct result that second drou magnirostris due to fortis big beaks being about. First drought occurred leading to increased bill size in g.fortis and beak size reduces a bit then when second drought occur to magnitrosis being around. The big beaked fortis didn’t do well in second drought as the maginstrosis ught didn’t fair well for s birds and then after g.magnitrosis comes rs, beak size dramatically drops in fortis due ey were competing with big beaked The big beaked fortis didn’t do well in second drought as the maginstrosis Different weasel species looking at canine diameter size Canine diameter, Gap between species of canine size is not random. Is due to re Lack of overlap of canine diameter across species Trait over dispersion - traits more widely separated than randomly generated/separated. Competition is giving out resource space Due to sexual selection? Hard to know what its due to ey were competing with big beaked esource allocation. you would see if they were