The price of deforestation

Matt Kaplan

Human impact on the living environment not only reduces the number of individuals in the population, but also causes individuals of some species to shrink their bodies.

Johanna Delgado-Acevedo and Carla Restrepo of the University of Puerto Rico collected specimens from two popular frog species in Puerto Rico from nine different locations in the northern archipelago.

These locations are all in the subtropical area with a humid climate, but each area is very different in the number of trees. Some locations are dense, others are almost empty, with no remnants of forest. Species frogs were taken with X-rays and bone size was measured.

Surprisingly, the team found that frogs in areas with forest cover range from 20% to 10% or 5% are smaller in size than frogs in areas with 70% or more forest area. They also found that frogs in a heavily disturbed habitat area had less body weight than those in quiet areas.

Problem about size

Delgado-Acevedo said: 'The size of the amphibians' body decreases when they face many predators, but the phenomenon of changing the size of the body due to the impact of human environment is really surprising.' .

Miniaturization may be the result of natural selection. With very few supplies available in deforested areas, smaller frogs with less demand will be the best adapters. However, the disturbed environment can affect frogs during their early stages of development when they are put into the environment with the pressure they have not experienced before.

It is difficult to know if resizing is good or bad. Small body sizes are often associated with slower movements, more heat loss, faster dehydration but easier hiding.

Eleutherodactylus antillensis frogs were included in the study.The frogs in the thin forest are 10% smaller than the frogs in the jungle.(Photo: Luis J Villanueva-Rivera)

Environmental tools

According to Delgado-Acevedo, 'small size also has some benefits, however this animal cannot shrink by itself from natural environment factors but due to human impact. We think this is not good. '

Endocrinologist Rachel Santymire takes on the work of identifying and influencing impacts on endangered species at Lincoln Park Zoo (Chicago, Illinois), saying: 'Frogs have opened the trend. It is very interesting to have further research '.

Delgado-Acevedo said: 'We think that body size and symmetry characteristics can be used as a tool to assess the status of natural populations'.

Santymire said: 'What I wonder about is whether pollutants, pathogens or competition cause shape changes in frogs residing in deforested forests'.

Article reference: Conservation Biology (DOI: 10.1111 / j.1523-1739.2008.00930.x)