Hot answers tagged

34

A mosquito is a biological parasite, it is not a medical parasite. There are two definitions of parasite. A biological/ecological definition and a medical/physiological interaction definition. A parasite in biological terms is an organism that benefits from a parasitic relationship; a parasitic relationship being a non-mutual relationship between species, ...


33

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 ...


33

TL;DR: it's a simplified measure of sustainability, but accurate enough to be useful for public engagement EOD is hosted and calculated by Global Footprint Network (GFN), an international think tank. The GFN estimates national and global net supply and demand for renewable resources, specifically: food and fiber products, livestock and fish products, ...


31

No, I don't think auto-regulation explain much in the population sizes of predators. Group selection may explain such auto-regulation 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 ...


27

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 ...


23

This is actually not a gall as other answers have suggested. This is likely a fungus called Cedar-apple rust (Gymnosporangium juniperi-virginianae). The fungus only thrives in the presence of both Juniperus virginiana (Eastern red cedar) and apple (Malus spp.) trees. The leaf in the picture belongs to some species of the apple genus and the growths are ...


22

A tiny Japanese puffer fish creates a grand sand sculpture on the featureless seabed by using his fins to dig furrows. He uses this to attract the attention of passing females. Why do puffer fish build sandcastles? (BBC) Further observation revealed that this “mysterious circle” was not just there to make the ocean floor look pretty. Attracted ...


21

There are a number of environmentally destructive methods that would be effective, including draining the lake, covering the surface with a continuous layer of oil, or adding toxins to the water, but I'm assuming you're looking for a method that will have the minimum possible off-target effect. Different mosquito species breed in different habitats and are ...


20

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. ...


19

You are absolutely correct in regards that marine life does cause damage to corals. In particular, parrotfish have been found to play an important role in regulating the biodiversity of coral reefs through their feeding behavior. Certain species of parrotfish feed on certain species of coral, typically faster growing species that branch out into easier ...


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, it will ...


17

I think that your question comes from a misunderstanding in the definition of the overshoot day, here is the definition in your question: Regardless of how it's calculated, the claim that we have today "overshot" our yearly earth-budget, at 8 months out of 12, means that we are consuming about 1.5 of the available food and natural resources available; or ...


17

The quick answer is: Yes, it can cause harm. Think about it...The septic system (both the tank and your "drain field") rely on bacteria, and antibacterial soap is not designed to kill only specific species of bacteria. In other words, antibacterial soap can kill a whole range of bacteria, and that certainly includes the bacteria needed in your ...


16

This "nest" is created by a male pufferfish for both courtship and for rearing young. The male puffer fish uses its body and fins (a combination of pectoral, anal, and caudal -- see here) to break up the sand into fine particles and to move it around into the pattern seen above. It swims in channel-like (or furrow) patterns to create the ray ...


15

General overview. Each toxin and poison probably have their 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 ...


14

Remi.b's answer is an excellent one, and this should be taken as a supplement to it: It's possible your simulation is correct The Lotka-Volterra equations are what is known as a deterministic model, and it describes the behavior of predator-prey systems (in a somewhat simplified fashion) in large populations. Small populations are subject to what is known ...


13

Adding some additional database sources: -- Climate -- Prism The PRISM Climate Group gathers climate observations from a wide range of monitoring networks, applies sophisticated quality control measures, and develops spatial climate datasets to reveal short- and long-term climate patterns. WorldClim WorldClim is a set of global climate layers (climate ...


13

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 a various source of nutrients. As a consequence, ...


13

It is protection against rapid warming of the cambium layer. A lot of far northern timber has light colored bark which reflects sunlight. The rapid heating from very cold after sunrise can actually damage or even split the bark of dark colored species. This is called sunscalding.


12

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 falls within the field of allometrics (how different features of organisms scale with body size). A closely related allometric relationship is Kleiber's law,...


12

According to a number of citations listed on Kenyon College's MicrobeWiki, rain can contain microorganisms via a process called "bioprecipitation." Essentially, microorganisms, dust and other small particles get swept up into the atmosphere, and cold temperatures cause atmospheric water vapor to freeze around the organism/particle. Once the ice-covered ...


11

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. ...


11

Short answer Female* mosquitoes are generally not to be considered ectoparasites because they spend so little time with the host. Instead, they are sometimes classified as micro-predators. *Male mozzies don't practice hematophagy at all Background According to some sources, the term parasite hinges on the time the parasite spends on, or in its host and ...


11

This article discusses the origin of the terms. They come directly from the equation used to describe population dynamics. As Canadianer mentioned the Wiki also covers it quite well. "r" stands for "rate" {growth rate}, r strategists have a high r value and a low K value. They grow fast but most die. "K" stands for Kapazitätsgrenzen which is german for ...


11

A recent studya measured the volumes (using a 3D scanner) and masses of 113 different insect species. They found the following relationship between the mass of the insects and their volumes ($V[mm^3]$ and $m[mg]$): $\ln (V) = 1.019 \ln (m) + 1.46$ $\Leftrightarrow V = 4.30596 m^{1.019}$ Thus, since $\rho = \frac m V$ $\rho(m) = \frac m {4.30596 m^{1.019}}...


10

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.


10

For species occurance data the Global Biodiversity Information Facility (http://www.gbif.org/) database should be an obvious choice. It contains both historical records from museums etc and information from more recent surveys and inventories. Note that the occurrence data can both come from standardized inventories and observational records from specialists ...


10

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 ...


10

Detritivores consume (eat) detritus. Saprotrophs feed on dead organic matter by the means of extracellular digestion. Saprozoic organisms are protozoans that are saprotrophs. This actually comes from an obsolete classification of plants and animals where bacteria and fungi were grouped with plants and were therefore called saprophytes if they are ...


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