BIO3021 Lecture Notes - Lecture 7: Intraspecific Competition, Ciona, Interspecific Competition
25 May 2018
School
Department
Course
Professor
Lecture 7 – Diversity, competition and Invasion in the Sea
Darwin
• Competition should be less intense among distantly related species
• Goats more related to cows than birds
• Why
o Closely related species use the same resources
▪ Draw resource down at a faster rate
▪ Results in hardly any population growth
• Increased niche overlap and competition → results in less growth
• More diverse communities: less niche overlap and competition → results in
more growth
Higher Diversity Populations have Higher Productivity
• Slight differences in resource utilisation leads to less competition
• Intraspecific competition should be stronger than interspecific competition
• Emergent property of high diversity communities → greater productivity
o Communities (of different species) will perform better on average than
populations of the same density
• But how much of a genetic difference is enough to generate these emergent
properties?
o Among guilds: different resource requirement → no overlap
o Among families
Arrangement of Small Scales Affects Productivity
• Clumping/aggregation reduces productivity over time
• Diversity of small scale affects productivity
Manipulating Genetic Diversity at Small Scales in the Field
• Little populations of small diversity
• Populations from different mums/ colonies at high diversity survive better and
grow faster over time than populations of the same mum
o Compete more intensely with siblings
• Increased genetic diversity → increased fecundity
What about More Subtle Differences in Genetic Diversity?
• Ciona intestinalis
• Unrelated individuals vs. Half-sibs vs. full sibs
• Higher genetic diversity → higher survival
o Step wise effects
o Survival at 4 weeks if unrelated – reasonable survival
o Share one parent – survival slightly lower
o Share two parents – survival much lower
▪ Settling next to siblings: performance is lower → avoids
• Genotype affects how much you overlap with someone else
• Bacterial biofilms
o Bacteria are genetically identical to each other but alter one gene – ask
how does changing one gene effect competition?
▪ Having high diversity → increases productivity
• Resistant to predation
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Lecture 7 diversity, competition and invasion in the sea. Darwin: competition should be less intense among distantly related species, goats more related to cows than birds, why, closely related species use the same resources, draw resource down at a faster rate, results in hardly any population growth. Increased niche overlap and competition results in less growth: more diverse communities: less niche overlap and competition results in more growth. Higher diversity populations have higher productivity: slight differences in resource utilisation leads to less competition, emergent property of high diversity communities greater productivity. Arrangement of small scales affects productivity: clumping/aggregation reduces productivity over time, diversity of small scale affects productivity. Marine invasion: artificially increase diversity, marine invasions have gone on for a long time, two waves of invasion, each with different vectors and different species. Vectors of first wave: lecithotrophs, filter feeders located on outside of ships, good competitors colonial (produce non feeding larvae, spend short time in plankton, less impactful.
