Alfred Russel Wallace - Who was collecting specimens in the Malay Archipelago, had independently conceived of natural selection.

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#XL - T Zoology

Quadrats - A square frame often, but not always, measuring 50 × 50 cm. 

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Pitfall traps set into the ground catch wandering species such as beetles and spiders. These have rain covers to prevent the animals from drowning

 

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Baited snap traps, Population density can thus be estimated as the number of animals caught per trap or per unit area where a given number of traps are set.

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The mark-recapture technique is that after the tagged animals are released, they mix freely with unmarked individuals. The population is resampled and the numbers of marked and unmarked individuals are recorded. 

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#XL - T Zoology

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#XL - T Zoology

Mark-recapture technique can have drawbacks;

1. Some animals that have been marked may learn to avoid the traps. 
2. Recapture rates will then be low, resulting in an overestimate of population size.