Tag Info

Hot answers tagged

20

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 ...


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 ...


13

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. ...


13

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 ...


12

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 ...


11

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 ...


10

Population dynamics occupies a whole subset of mathematical biology. Perhaps the most pragmatic uses for modelling population dynamics come from the fields of epidemiology for modelling disease infection and transmission through a population (one such article), or ecology modelling things like forestation, fishing dynamics, predator-prey relationships (an ...


10

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

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. You'll be interested in various model of prey-predator or of consumer-ressource interactions. as @shigeta said, what the following says is: predators ...


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 ...


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

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 ...


7

Two previous answers listed many applications of population dynamics models. I want to add that they are also important for conservation of endangered species. For example classical stage-class model (Crouse et al 1987, free copy) indicate that the most effective way to protect sea turtles is reducing mortality of large juveniles. Moreover, you don't have ...


7

The distribution of temperate hardwood forests, as well as deserts, tundras, savannahs, and other ecosystems, is determined primarily by average climate conditions, specifically average annual temperature and precipitation. You can see how biomes are related to climate in this figure, taken from Whittaker (1975): Temperate forests tend to be between ...


7

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 ...


7

Trees need: Deep roots to get more water and anchor their growth. Strong trunks to support themselves against gravity. A vascular system to move water and nutrients throughout the tree. Small leaves that can be supported high by the trunk to compete for sunlight. Water plants need: Just enough root to anchor its location. No vascular system. Water is ...


6

There does not appear to be a current standard, but Veg-X is a standard that has been developed to facilitate exchange of plot-based vegetation data, and may provide the closest to what you are looking for. Veg-X is described in Wiser et al 2011 and the project home page is http://wiki.tdwg.org/Vegetation/ From the abstract: The exchange standard for ...


6

That will depend on many things. How do you define surface? Is one meter underground still "surface"? How about a kilometer? Also, how large an area are we talking about? You could probably find a square millimeter in, for example, Antarctica that has no organisms. I don't think you would find a square kilometer with no organisms though. There are ...


6

From How Do Pine Cones Open (Nature): The scales of seed-bearing pine cones move in response to changes in relative humidity. The scales gape open when it is dry, releasing the cone's seeds. When it is damp, the scales close up. The cells in a mature cone are dead, so the mechanism is passive: the structure of the scale and the walls of the cells ...


6

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 ...


6

The answer to your question is in the first graph of the Wikipedia article you linked to: Great Oxygenation Event. In that graph, where time is measures in billions of years, you see that O2, as it was produced, was absorbed in oceans, seabed rock, land surfaces, and finally, about .85 billion years ago, O2 sinks filled and the gas accumulated in the ...


5

I guess you meant the population size stability. It is considered that the biosystems will increase their capacity of adaptation when evolving in very fluctuating environments. I believe the population stability is embedded in the adaptability of individuals. There is a measurement about it, evolvability, when the environment changes, the faster the ...


5

I'm not an expert on Shannon-Weaver Index, but according to wikipedia it is the same as exponentially transformed Renyi entropy. If it is the case, you can compare them since they are scale invariant summary statistics. If you want error bars, you can always try resampling methods such as bootstrapping. Hypothesis testing can also be done with bootstrapping, ...


5

There are many websites which describe this phenomenon. They all seem to confirm the basic premise of the question: in tropical rain forests most of the minerals are held in the biomass and rapid decomposition contributes to the recycling of these nutrients for new growth. One example is here. Tropical rainforests are noted for the rapid nutrient cycling ...


5

Barring the very obvious surfaces (the pits of active volcanoes), the only place I'm aware of that might not contain life is the Atacama Desert near the Andes Mountains in Chile and Brazil. Whereas other places that seem inhospitable - Antarctic, Hot Springs, regular deserts, extremely high altitudes, etc. - the basic necessities for life still exist ...


5

if the pool were just sitting out in open air, on earth and all that good stuff, it certainly would, given enough time. This thought experiment is in the same vein that inspired Darwin when he reflected on his experiences on his visit to the Galapagos islands. Think about it - the many islands which are formed by upheaval were lifeless when they first ...


5

Although work in those areas is definitely all related, there are some kind of general differences in how those labels tend to be used, and I'll take a stab at defining them: Mathematical ecology - this is typically the creation of theoretical models composed purely from math (i.e. not stochastic computer models). Examples include a lot of classics from ...


5

There is not very much transport of ions or water through the upper layer of the skin, mainly responsible for that is the stratum corneum (SC). Through this layer you will get only with small lipids and also substances which are able to penetrate the lipid layer of the cells like chloroform or DMSO. I think therefore that it is pretty unlikely that you can ...



Only top voted, non community-wiki answers of a minimum length are eligible