Invasive and Keystone Species

Yellow Star Thistle

Yellow Star thistle is an invasive species that is native to Eurasia, and was introduced to the US in the 1800's. It is believed that the species was introduced through accidentally contaminated seeds. Although the yellow star thistle doesn't have a huge impact on the environment, it crowds out native species and can be potentially toxic to horses. When ingested, the plant causes a neurological disorder called equine nigropallidal encephalomalacia or chewing disorder. If horses continue to feed on yellow star thistle, brain lesions and mycosal ulcers in the mouth may form which eventually leads to death. The bright yellow looking flower has sharp spines that have been known to puncture tires.

Yellow star thistle is a relative of knapweed and its yellow flowers. This plant is an annual that can grow up to three to five feet in height. Leaves and stems are a grayish-green color and leaves are covered with cottony wool. Lower leaves are up to 3 inches long and deeply lobed, while upper leaves are short and narrow with fewer lobes and give the stems a "winged" appearance. Flowers are bright yellow and sharp spines up to ¾ inches in length surround the base of the flower. Each plant cant produce up to 150,000 seeds making it really easy to spread. They typically thrive in sunlight with deep soils. It is often found in disturbed areas, roadsides, rangelands, waste areas, overgrazed lands, pastures, hay fields, along waterways, roadsides, forests and other non-crop areas. The best removal method of yellow star thistle is herbicides, however hand pulling and mowing are also effective methods of eradication. Yellow star thistle has no known economic value it is just like any other weed that people want to get rid of.

Yellow Star Thistle and Distribution Map.

Jaguars

The jaguar is at the top of the food chain so it is an apex predator. It is also a keystone species, having a major role in an ecosystem. It feeds on a a lot of prey and regulates the populations of these native animals, creating a balanced environment. If the jaguar disappeared, the ecosystem would change drastically and could result in disastrous consequences.

Jaguars are fast and muscular predators that can chase down even the fastest of animals. There short stocky stature allows it to crawl, climb and swim. Jaguars are typically yellowish orange and have dark rosettes for camouflage. Jaguars have a very powerful bite that is used as its primary method of attack. There bite is so powerful it can pierce through the skull of its prey. There bite is twice as strong as a lions. The jaguar hunts by stalk and ambush, pouncing and attacking on its prey making it very hard to escape. Male jaguars have territories that do not overlap due to competition and resource limitations. The lifespan in the wild is anywhere between 12 to 15 years.

Jaguars are the national animal of Guyana and Brazil. Jaguars are considered near threatened and there numbers are declining. One threat is habitat loss and fragmentation from deforestation. Farmers in South America will kill jaguars if they threaten their livestock, and the skins can be sold for a lot of money. Jaguars are protected better in some places then others, but its broad home range and habitat ensures the protection of other species in there ecosystem. If jaguars were to go extinct, the entire ecosystem would be changed.

Golden Toad

The golden toad was a small, bright orange toad that lived in the high-altitudes of Costa Rica. The species was distributed over an area of 3.9 square miles an elevation of 4,900 ft. Adult golden toads were only five cm long. The florescent color of the toads was beautiful. Most toads don't have shiny and bright skin, but the golden toad did. Female golden toads are slightly bigger than males and looked very different. The female toads were dark olive colored with scarlet spots .

Not much is known about golden toads reproduction, most of the year they lived underground except during mating season, which lasted for a few weeks. Eggs of the toads were laid in seasonal water droppings. After two months the eggs hatched into tadpoles. The amount of male golden toads outnumbered the females up to 10 to 1. The lack of females led to competition during the mating season. If the water the eggs were kept in dried up, they wouldn't survive and if rain-washed the eggs away they wouldn't survive. The drying of the forest ground made it nearly impossible for the golden toad to populate.

Little could be done to prevent the extinction of the golden toad. Their environment made it hard to reproduce which made them a threatened species until extinction. The number of golden toad spotting's gradually decreased each mating year until they were no longer seen. Researchers hope that the species has survived in underground burrows. The golden toad went on the extinction list in 2004. Restricted range, climate and airborne pollution could have led to the extinction of the golden toad. El Nino has caused the spread of chytrid funus due to the dry conditions.

Jaguar Native Habitat