Why are monarch butterfly’s toxic?

#Question id: 12294

#Section 1: Ecology

#Question id: 4713

#Section 2: Evolution

A farmer uses triazine herbicide to control pigweed in his field. For the first few years, the triazine works well and almost all the pigweed dies; but after several years, the farmer sees more and more pigweed. Which of these statements explains why the pigweed reappeared?

#Question id: 10820

#Section 1: Ecology

Of the following types of interactions, which one is least likely to limit population size?

#Question id: 10659

#Section 2: Evolution

Ecological and crude density of fish prey in related with predator. Water level is drop during the dry season and further increases in a rainy season. Following some observation effect are present on their density

 A) Ecological density is not change with respect to water level       

 B) Ecological density is gradually decrease with low water level

 C) Crude density increases over ecological density during low water level             

 D) Ecological density increases while crude density decreases during low water level

 E) There is no effect on crude density with seasonal water level

 Which of the following above observation is correct?

#Question id: 10247

#Section 1: Ecology

Deciduous oak habitats in southern Europe are superior to evergreen oak habitats from the perspective of the blue tit, a small songbird. As a result, blue tit populations in deciduous oak habitats have more potential for __________ and serving as __________ populations.