It's All About the Interactions

Source: Food and Agriculture Organization of the United Nations, 2013, Christine Gibb, CBD and FAO, "The Youth Guide to Biodiversity" 1st Edition (Chapter 1) Youth and United Nations Global Alliance. Reproduced with permission.

Chapter 1. Author, Christine Gibb, CBD and FAO. Verbatim.

Perhaps the most important characteristic of biodiversity is that all of the components are linked to each other.  

For example, if a mouse eats a chemically-contaminated seed, it may survive, but if a hawk eats many mice that have eaten such seeds, the hawk may die from a lethal dose of the chemical. Because of their position in the food chain, top predators such as hawks are susceptible to such biomagnification, the accumulation of substances that increase in concentration up the food chain.

Biodiversity linkages can also be beneficial: the restoration of coastal mangrove forest ecosystems provides an important nursery habitat for fish and other marine species, improves fisheries along the coastline, and protects human settlements from extreme weather events Similarly, the re-naturalisation of upstream rivers allows the recreation of a natural food chain, decreases the amount of mosquito larvae (thereby decreasing the incidence of malaria or similar mosquito-borne diseases), improves fisheries,and purifies water. If one level of biodiversity is interrupted, the other parts experience a ripple effect, which can be harmful or helpful to biodiversity.
The box: “Smaller Habitats Lead to Smaller Gene Pools” shows how the deterioration of an ecosystem negatively affects both species diversity and genetic diversity.

The box: ”The Black Bear and the Salmon: Mighty Ecosystem Engineers” illustrates one positive example where two species play vital roles in engineering an ecosystem.

 Smaller habitats lead to smaller gene pools

The Florida Everglades in the USA is a unique ecosystem that was once home to many wading birds, mammals, reptiles, insects, grasses, trees and other species. It used to cover an area as large as England (over 9 300 square kilometres), but has shrunk over the years as more and more people moved there. 

The people also changed the ecosystem by building water management areas and canals, and filling in swampy areas for agriculture. These ecosystem changes were bad for many species, including wood storks and Everglade kites.

The changes even affected the genes of some species such as the Florida panther! As suitable habitats were broken up into smaller and smaller pieces (scientists call this process “fragmentation”),only a few Florida panthers could survive. 

With fewer breeding partners around, the variety in the gene pool (the total variety of genes available) declined. So the changes to the ecosystem negatively affected both species diversity and genetic diversity. 

Sources: www.biodiversity911.org/biodiversity_basics/learnMore/BigPicture.html and www.nrdc.org/water/conservation/qever.asp