Ecology and Evolution Flashcards
physiological ecology
the study of an organism’s physiological response to its environment
Life history strategy: r-strategist
R-strategists “live” near the line of exponential growth r; often live in unstable environments; evolved to develop as many offspring as possible, ensuring that at least a few will survive their harsh environment; offspring are often small in size; do not depend on parents for long, they grow and start reproducing on their own quickly
Life history strategy: k-strategist
near the carrying capacity k on the population growth curve; under stable environment conditions; focusing their energy on generating a few, healthy, complex offspring that can receive ample care so that they go on to survive till adulthood;
Life history strategy
how organisms divide their resources into survival, growth, reproduction and parental care
neutral theory
most sequence variation within and among clades is driven by genetic drift acting on selectively neutral mutations, most mutations are deleterious and therefore are rapidly removed by selection, most non-deleterious mutations are neutral rather than beneficial, and will therefore tend to drift to fixation in populations
pseudoreplication
The use of inferential statistics to test for treatment effects with data from experiments where either treatment are not replicated (though samples may be) or replicates are not statistically independent.
types of pseudoreplication
simple, sacrificial, and temporal
simple pseudoreplication
samples are grouped together in a way that creates nonrandom differences between groups that don’t include ‘treatment effects. For example, two separate plots where all experimental organisms are in one plot, and all control are in the other
sacrificial pseudoreplication
data is pooled prior to statistical analyses or 2+ samples taken from each unit treated as independent replicates
temporal pseudoreplication
samples aren’t taken from experimental units (like in simple pseudoreplication) but sequentially, creating nonrandom differences between grouped samples
why non-native species behave differently in systems they’ve invaded compared to their native systems? theories/ideas
novel weapons hypothesis, enemy release hypothesis, propagule pressure, biotic resistance
enemy release hypothesis
invasive species are less impacted by enemies (e.g., herbivores) than native species, because in the new geographical location, the invasives species are freed from the parasites, pathogens, and predators that kept their growth in check in their native environment. For example: zebra mussels in North America. Fish and especially waterbirds in their native habitat in Eurasia keep them in check, but the organisms in North America did not coevolve with zebra mussels, and do not consume them at a high enough rate to control their population growth. Argument against: not all non-native organisms become invasive.
novel weapons hypothesis
some invasive species may be successful due to “unique allelopathic, defense, or antimicrobial biochemistry to which naïve native species are not adapted” (He, et al., 2009). Callaway and Ridenour, 2004 (proposed this hypothesis) suggest that “some exotics transform from native weaklings to invasive bullies by exuding biochemicals that are highly inhibitory [allelopathic] to plants or soil microbes in invaded communities, but relatively ineffective against natural neighbors that may have adapted over time. Example: some species were outcompeted by diffuse knapweed in its non native range compared to its home range, did experiments and found some chemical in knapweed roots that inhibited species not found in home range much more than those from home range (evolved tolerance). Argument against: little evidence.
propagule pressure
composite measure of the number of individuals of a species released into a region to which they are not native. It incorporates estimates of the absolute number of individuals involved in any one release event (propagule size) and the number of discrete release events (propagule number). Propagule pressure can be defined as the quality, quantity, and frequency of invading organisms (Groom, 2006). Propagule pressure is a key element to why some introduced species persist while others do not (Lockwood, 2005). Species introduced in large quantities and consistent quantities prove more likely to survive, whereas species introduced in small numbers with only a few release events are more likely to go extinct (Lockwood, 2005). Example: cheatgrass produces a lot of seeds, and also goes to seed a lot earlier than native plants, so it has a high propagule pressure.
biotic resistance hypothesis
Charles Elton (1958) predicts that species-rich native communities limit the niche space available to other species, and thus more diverse communities have greater biotic resistance to incoming non-native species. Example: non-native plant occurrence was negatively related to native plant richness across all community types and ecoregions, although the strength of biotic resistance varied across different ecological, anthropogenic and climatic contexts (Beaury, et al. 2020).
biodiversity
Biological diversity refers to the global variety of species and ecosystems and the ecological processes of which they are part, covering three components: genetic, species and ecosystem diversity
Latitudinal diversity gradient
The gradient involves high species’ numbers near the equator (at low latitudes) and lower numbers of species at high latitudes. Lack of consensus about why, but some likely theories are: increased solar energy increases net primary productivity; more stable and tolerable climate at lower latitudes, allows organisms to use their energy for reproduction instead of thermoregulation (ecological regulation hypothesis); effective evolutionary time - habitats with a long undisturbed evolutionary history will have greater diversity than habitats exposed to disturbances in evolutionary history, tropical conservation hypothesis states that higher latitudes have the capacity to have higher diversity but are younger and thus have not had the time to build higher diversity levels such as those found in lower latitudes; diversification rate hypothesis postulates that species rich clades diversify more rapidly
drivers of biodiversity
Latitudinal diversity gradient (+), niche filling (+), climate change (-), gene flow (+)
importance of biodiversity
maintain healthy ecosystems; decrease invasive species invasions; safety net when a species is lost, others can fill its role; high genetic diversity means higher ability to adapt to new environmental conditions
drivers of genetic diversity
mutation, novel recombination, and gene flow
genetic recombination
the exchange of genetic material between different organisms which leads to production of offspring with combinations of traits that differ from those found in either parent
evolutionary significant unit
a population of organisms that is considered distinct for purposes of conservation; often a species; often include: current geographic separation, genetic differentiation at neutral markers among related ESUs caused by past restriction of gene flow, or locally adapted phenotypic traits caused by differences in selection.
Pros and cons of conserving ecological and evolutionary processes, rather than preserving of specific phenotypic variants - Moritz (1999)
Can still help individual species, but focusing more on overall eco and evo processes until extinction rates begin to decline; gene flow (via connecting fragmented habitats) helps populations, especially small ones; increase genetic diversity; certain phenotypic variants may be well suited for their current environment, but if they don’t have sufficient underlying genetic diversity, they will not be able to adapt to environmental changes; however, may lose certain species that are needed, like keystone species, if they aren’t given enough individual attention
Types of direct interactions
competition, predation, parasitism, mutualism (not all)