Communities and Ecosystems

Nature is a mosaic of complex interactions and relationships between animals, plants, and their environment. Individual organisms belong to populations, species, communities, and ecosystems. Energy flows from one organism to another and it is through these relationships that populations influence each other and the environment. Find out more about community and ecosystems.

Communities and Ecosystems

Nature is a mosaic of complex interactions and relationships between animals, plants, and their environment. Individual organisms belong to populations, species, communities, and ecosystems. Energy flows from one organism to another and it is through these relationships that populations influence each other and the environment. Find out more about community and ecosystems.

Brittle Stars and Basket Stars Echinoderms with Inflexible Arms

Like sea stars, brittle stars and basket stars have (in most species) five arms (which in some species are highly branched). But the arms of brittle stars and basket stars differ from those of star fish in that their central disk is easily distinguished from their arms (in starfish, the arms blend with the central disk such that it is difficult to see exactly where the two meet).

Brittle stars are so named because their arms can only move side to side and not up and down. If their arm is forced either up or down, it breaks. The lateral arm movements used by brittle stars and basket stars enables them to crawl across the substrate or cling to surfaces. There are about 2000 species of brittle stars and basket stars and they exhibit a range of feeding methods from filter feeding to scavenging to predation.

Older Male Sparrows Not Threatened by Younger Males

Older male white-crowned sparrows don't see younger male sparrows as much of a threat. When vying for mates or squabbling over territory, older males don't often bother challenging their younger rivals because they pose little credible competition. Instead, they only pick a fight with other older males that could pose a significant threat to their superiority.

It turns out, the way these birds figure out each others' seniority is based on their songs as well as their plumage. Male white-crowned sparrows use song for multiple purposes including attracting a mate and claiming their territory. Since young male white-crowned sparrows sing differently than older males, song can be used to distinguish age.

After mapping the territories of 16 male white-crowned sparrows, the research team was able to observe how males of different ages responded to songs made by intruders.

They found that older birds did nto react as strongly when they heard the song of a younger bird in their territory.

Photo © Douglas Nelson / Ohio State University

Lemurs Dont Fill Niches Left Open by Extinctions

Recent research has revealed that when one of two competing lemur species goes extinct, the surviving species does not thrive. In fact, data examined by the research team shows that over the past 2,000 years, when a species goes extinct, the surviving species is vulnerable to new selective pressures that can actually increase the likelihood that it too will go extinct.

The research team, which included scientists from the University of Cincinnati and University of Massachusetts at Amherst, used radiocarbon and isotope data from fossils from eight large lemur species that have gone extinct on the island of Madagascar during the past 2,000 years. They found that after the larger lemurs disappeared, the remaining lemurs did not expand into the available niches.

Photo © Brooke Crowley / University of Cincinnati

Thailands AntiPoaching Efforts Paying Off

Anti-poaching efforts are successfully helping to protect many rare species in Thailand, according to a recent report by the Wildlife Conservation Society (WCS). Videos and images collected from WCS camera traps provide park rangers much needed data that can be used to arrest and convict poachers. Additionally, camera trap information is used by Wildlife Conservation Society scientists to measure and track population sizes of numerous local species.

The camera traps, placed in multiple locations within Thailand's Western Forest Complex, have capture footage and pictures of a variety of species including wild pigs, leopards, tigers, gaurs, Asian elephants, sun bears, clouded leopards, banteng and many others. Camera trap data indicates that there are between 125 and 175 tigers living within the 18,000-square kilometer Western Forest Complex.

Thailand serves as a critical front in the battle against poachers. The WCS has joined forces with the Thai government to train park rangers how to protect the region's rare animals from illegal hunting. Many park rangers and wildlife guards from other Asian countries are trained in Thailand, so they can learn how to best protect the rare wildlife from poaching in their own countries.

Photo © DNP-Government of Thailand / WCS Thailand Program. Camera trap image of an Asian elephant calf in a heard of adults, photographed in the Western Forest Compex, Thailand.

Understanding the GoldenCrowned Sifaka Population Decline

Scientists have recently proposed that the population of golden-crowned sifakas in the Daraina region of Madagascar declined prior to the arrival of humans to the region. The team also examined 60 years of satellite images and determined that forest cover in the region has remained stable during that time period. The findings contradict the widely held belief that the decline of golden-crowned sifakas is due to recent human activities and their effects, such as deforestation and climate change.

Although there is no denying that climate change and deforestation do result in loss of biodiversity and the drastic decline (or extinction) of many species, the case of the golden-crowned sifaka may be more a case of natural decline than man-caused decline.

The research suggests that the open habitats of Madagascar's Daraina region are the consequence of climate changes that took place prior to the arrival of humans. These pre-human climate changes, which included droughts during the Holocene, reduced the golden crowned sifaka's preferred habitat.