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32

There are (at least) three important factors to consider here; evolution under selection requires genetic variation upon which to act, selection can act on covarying traits causing trade-offs, and adaptation also occurs in the predator. A lot of this is covered elsewhere on this site (including the effects of the other mechanisms of evolution), but little ...


21

The conservation biology literature has a great deal of information, particularly with reference to developing species survival plans (e.g., Traill et al. [2007] report a minimum effective population size of ~4,000 will give a 99% persistence probability of 40 generations). Because the question specifically mentions human populations, I'll focus my answer ...


17

There are two reasons for this: evolutionary trade-offs and coevolution (the "Red Queen hypothesis", as mentioned in the comment above by Luigi). Evolutionary trade-off describes situations where one trait cannot increase without a decrease in one or more others. Some hypothetical examples: longer legs may help run faster but past a certain point will ...


16

No, I don't think auto-regulation explain much in the population sizes of predators. Group selection may explain such auto-reagulation but I don't think it is of any considerable importance for this discussion. The short answer is, as @shigeta said "predators tend to starve to death as they are too many!" To have a better understanding of what @shigeta ...


15

While poison affects not every organism equally, plants did develop some poisons to avoid being eaten. However, if you look at the great multitude of so-called secondary metabolites, most of them are poisonous to either viruses, bacteria, fungi or other microorganisms, or insects, or even other plants. Plant evolution just hasn't had time to adapt to humans. ...


15

A hormone is defined as "a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism" (I'm just taking Wikipedia definition). Hormones work by binding to specific receptors present on their target cells so, if there is something in the environment that mimics the hormone, by ...


15

It is difficult to find a scientific answer to this question, but let me insert this citation from a specialist site: Contrary to popular belief, beaver cannot plan the direction in which trees will fall. Many trees become hung up in the branches of surrounding trees and are lost to the colony. In heavily forested areas, this loss may amount to one-half ...


15

Food hierarchy and food web Ecological trophic interactions are better represented by food webs rather than simple hierarchical relationships. As a consequence, the concepts of primary/secondary/tertiary/... consumers sometimes poorly apply to reality. Obligate and Optional Many species are able to feed on various source of nutrients. As a consequence a ...


14

There are several key ways in which rising atmospheric CO₂ concentrations will affect photosynthesis, and these are related to the different types of photosynthesis. In order to properly answer your question, I'll provide some background about photosynthesis itself. Photosynthesis evolved in a high-CO₂ atmosphere, before the oxygen-enrichment of the ...


13

I did some research on the topic and came accross this paper by Johnson et al. I am not a zoologist, so everything I write here is taken from the references paper. The authors used genetics to estimate gene flow between different populations of limpets Lepetodrilus fucensis which is considered to be an endemic hydrothermal vent animal. They used a ...


12

I wanted to add a little more to the excellent answer above, especially since the OP asks about research into this question in a "real-world context". There is a substantial body of evidence on exactly this question that comes from experiments at "Free Air CO2 Enrichment" (FACE) sites. FACE is an experimental method/technology in which standing ecosystems ...


11

Following up on Alexander's response, I read a little more on the subject by looking at some of the references in the Johnson et al. paper. This paper discusses an interesting case where researchers could study a hydrothermal vent ecology before and after a catastrophic eruption giving a "natural clearance" experiment. Since endemic organisms were ...


10

General overview. Each toxin and poison probably has it's own evolutionary "arms race". Generally an organism contains a compound that is a bit harmful to other species. As a predator or prey species becomes tolerant to low doses of this compound through natural selection, the compound efficacy could be increased (again by natural selection) on a molecular ...


10

There are both costs and benefits to being able to run faster, both as a predator and as a prey animal. In short, maintaining the large muscles necessary to outrun a cheetah every time is metabolically expensive. So it isn't a matter of being able to always outrun a predator--it's a matter of how to optimally allocate precious resources either to ...


9

You can access the Imperial College global population dynamics database. They will have time series data at specific locations. http://www3.imperial.ac.uk/cpb/databases/gpdd There is a sister database as well that might be useful. http://lits.bio.ic.ac.uk:8080/litsproject/ These contain several hundred time series, and you can see a paper that used them ...


9

Basically, they don't. Ecosystems are pretty much either de facto, delimited by geographical boundaries, or defined by us. For example, an underground lake would be an ecosystem and it is organized in such a way for the simple reason that there is no communication between it and any other system. Most ecosystems however, do communicate. For example, we ...


9

Flies see motion. When the monitor screen changes, the visible spectrum of the pixel is changing and nothing is moving. Flies have limited color vision. Each color has its own wave frequency, but flies have only two kinds of color receptor cells. This means they have trouble distinguishing between colors, for instance discerning between yellow and white. ...


9

It is certainly possible to use general relationships to predict human population density or abundance. The relationship between population density/abundance and body size is an old topic in ecology, that fall within the field of allometrics (how different features of organisms scale with body size). A closely related allometric relationship is Kleiber's ...


9

Are you looking for 'Home range' (see also the definition in Encyclopaedia Britannica)? Generally, 'home range' is defined as the entire area an individual animal uses, while the 'territory' is the subset of the home range that is actually defended from conspecifics (in animals that show territoriality). 'Home range' is often delimited by the types of ...


9

Feral camels have environmental, economic and cultural impacts in Australia's Northern Territory (Dept of Land Resource Management, Australia). In central Australia, camels feed on more than 80% of the available plant species. Feral camels severely defoliate and suppress the recruitment of some shrub and tree species, with such impacts being greatly ...


9

The behaviour that you describe is common in most animal species, as part of the natural trade-off between access to food, minimizing risk, habituation and hunger. Animals usually choose to forage in high-quality habitats that has a low risk of predation, but if food sources are depleted (or competition and/or territoriality is high) they will move to other ...


8

Leonardo's already given you an excellent answer, but I thought I'd add my perspective. I'm a mathematical epidemiologist, so I'd at least like to believe these types of models are useful. For me, there are a number of things population dynamics models are especially useful for: Highlighting data requirements. Yes, models need data, as you've mentioned. ...


8

I think it does make sense - with a population density for finland that is so low, the disease with such a low beta cannot communicate to enough people to propagate. The number of people who have this disease will be fewer each week. I think this makes sense because at 16 / km^2, you can expect that practically nobody will ever see each other. This is ...


8

For climate related data you can start from Realclimate pages on data repository. For ecological data I always found less global data, but a good starting point may be the Ecological Society of America Data Registry page. An overview of repositories can be found the the Simmons University Open Access Directory.


8

Yes, they are behaving differently because of the lack of nutrients, including lactose, and possibly because of the presence of other chemicals in soy milk that aren't in dairy. Kefir grains are a complex community of different types of lactic acid bacteria and yeasts which metabolize (eat) various nutrients/chemicals in their environment. Because soy milk ...


8

I don't think one can fully answer to such a broad question. It depends on the population, the environment (presence of predators for example), the genetic background (having a big stomach is good but only if the intestin is big too), the population's social relations, .. Many traits are correlated and one might want to say that a given trait is beneficial ...


8

It is hard to find any articles on the association between Penicillium and Aspergillus species, although they are both considered two of the most common mold species found indoors. In this study, the most prevalent spore types detected in both the indoor and outdoor air samples were generally from the Penicillium/Aspergillus group [...] these findings are ...


8

Short answer: Changing something (instead of everything) yes. There are several studies on the impact of environmental factors on life span. Of course it depends from organism to organism. Diet restriction for example has been shown to extend life span of worms and mice. Temperature is also working well, at least with microorganisms, the metabolism of ...



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