Common coquí
The common coquí, widely known as the coquí, is a species of frog native to Puerto Rico belonging to the family Eleutherodactylidae. The species is named for the loud call the males make at night, which serves two purposes; the "co" serves to repel other males and establish territory while the "quí" serves to attract females. The auditory systems of males and females respond preferentially to different notes of the male call, displaying sex difference in a sensory system. The common coquí is a very important aspect of Puerto Rican culture, and it has become an unofficial territorial symbol of Puerto Rico.
Taxonomy
The common coquí was described as a species new to science by Richard Thomas in 1966. It belongs to the genus Eleutherodactylus which in Greek means free toes. This family is also known as the "robber" or "thief" frogs. This genus contains 185 species, which are found in the Southern United States, Central America, South America, and the Caribbean. It is part of the order Anura, which includes all frogs and toads. The scientific name of the common coquí, Eleutherodactylus coqui, was first described by Spanish naturalist José Félix de Arroyo de la Cuesta, in 1875. The genus Eleutherodactylus, of which the common coquí is a member, is the largest genus of frogs in the world, with over 700 known species. The common coquí is closely related to other members of the Eleutherodactylidae family, including the Eleutherodactylus jasperi and the Eleutherodactylus portoricensis. These species are all native to Puerto Rico and are distinguished from each other by their physical characteristics and vocalizations. This taxonomic classification reflects the evolutionary relationships between the common coquí and other species within the animal kingdom.Morphology and lifespan
Full-grown male coquís measure, from snout to vent, from, with an average of, while full-grown females measure from, with an average of. The elevation of the coquí's habitat affects their size. Areas with higher elevation have larger coquís. The size differences between sexes are a result of additional energy consumption related to breeding behavior by males.Coquís are muddy-brown in mottled coloration on the top with rust-tan flanks and a light-gray belly. As tree frogs, Coquís possess sticky pads on the tips of their toes which help them adhere to moistened or slippery surfaces They do not possess webbed feet and are not adapted to swimming.
The known lifespan of the common coquí is up to 6 years in the wild, but the majority of adults do not live past one year. The species is generally believed to have a relatively short lifespan, with most individuals living for less than a year. In a study of the population dynamics of the common coquí, researchers found that the species has a high mortality rate, with only a small proportion of individuals surviving to reach adulthood. This high mortality is likely due to a variety of factors, including predation, disease, and competition for resources.
Evolutionary morphology
A study by Lawrence and Stewart aimed to explore the spatial and temporal variation in color pattern morphology in the Coqui frog population in northeastern Puerto Rico. The researchers recorded pattern morphs for 9,950 frogs captured at nine locations over a 25-year period. The data revealed 21 distinct pattern morphs, including stripes, bars, and spots. Significant differences in morph frequencies were observed among locations, with longitudinal stripes more common in grassland, and spot and bar morphs more common in forests. The analysis also showed temporal shifts in morph frequencies immediately following Hurricane Hugo in 1989, indicating that the pattern polymorphism is influenced by major habitat disturbances. The researchers suggested that the polymorphism is maintained, at least in part, by local habitat matching driven by selection pressure from visual predators.The coquí is preyed upon by various vertebrate and invertebrate predators. The study explored the evolutionary adaptations in color and pattern variations that reduce the risk of predation. The concept of camouflage, cryptic coloration, and disruptive patterns were discussed in the context of predator-prey interactions. The researchers hypothesized that the pattern polymorphism observed in Coqui frogs is a result of selective pressures from visual predators, primarily birds, which develop search tactics and perceive the color patterns of their amphibian prey. The paper also discussed the potential factors influencing pattern polymorphisms, including apostatic selection and local habitat matching. The authors suggested that these factors, along with the likely heritability of pattern morphs, contribute to the maintenance of multiple patterns in the Coqui population.
Native and invasive habitats
Native distribution
Common coquís are native to the islands of Puerto Rico, Vieques and Culebra, where they are widespread and abundant; the only notable exception occurs in Puerto Rican dry forests, where the species is rarer. The common coquí is the most abundant frog in Puerto Rico, with densities estimated at 20,000 individuals/ha. Densities fluctuate depending on the season and habitat. Generally, densities are higher during the latter half of the wet season and decrease during the dry season. The species is considered a habitat generalist, occurring in a wide range of habitats, including mesic broadleaf forests, mountains, and urban areas, found in bromeliads, tree holes, and under trunks, rocks or trash. Since the species does not require bodies of water to reproduce, they can be found on most altitudes, provided sufficient moisture is available. In Puerto Rico, they are found from sea level to a maximum of. Adults generally tend to be found at higher altitudes than juveniles.The common coquís are often found in cohabitation with humans. Because of their unrestricted habitat use, E. coquí can commonly be found in homes and parks. E. coquí are found in natural habitats including the human mountain forest at elevations less than 1,200 meters and in the dry forest. They are found specifically within the under story of forests at all elevations up to the canopy.
Invasive population distribution
The species has been introduced to Colombia, Hawaii in the United States, and the Virgin Islands. It has become a densely populated invasive species in the Hawaiian Islands, where it was accidentally introduced in the late 1980s, most likely as a stowaway on potted plants, and quickly established itself on all four major islands. It is now considered a pest species by the State of Hawaii, and in the year 2000 it was put on IUCN's list of 100 of the world's worst invasive species. As an invasive species, it can reach up to 91,000 individuals/ha, almost 5 times its maximum density in its native Puerto Rico. Higher densities in its invaded range are likely bolstered by a release from native predators, lack of interspecific competitors, and abundant food availability. In Hawaii, they have been found at a maximum of above sea level. They were previously introduced in the Dominican Republic and to Louisiana and Florida, but these populations have now been eradicated.Common coquís in areas where their density exceeds 51,000/ha could consume over 300,000 invertebrates per night. Because of their large populations, Hawaii worries about both economic and ecological impacts. The common coquí currently costs this state nearly 3 million dollars a year. Its spread has been commonly through the nursery trade, and as a result many people are reluctant to buy plants from nurseries that might be infected. Those began to perform quarantines and de-infestations in order to improve their prospects. Coquis also affect real estate values in residential neighborhoods, as many refrain from buying houses where their sleep would be disturbed by the up to 73 dB call of the common coquí.
Diet
The common coquí is a generalist nocturnal predator, which can consume, as a population, 114,000 invertebrates each night per hectare. Diets vary depending on age and size, but are primarily composed of arthropods. Juveniles consume smaller prey, such as ants, while adults consume more varied diets that include spiders, moths, crickets, snails, and small frogs. The frogs are opportunistic sit-and-wait predators, and will forage on any abundant prey. Males will occasionally consume eggs from their own clutch, likely to provide supplemental nourishment while guarding their nests.Calling males eat less prey than quiet males, which consume most of their food by midnight, while calling males had eaten only 18% of their food by the same hour.
Native ecological impact
Experiments conducted in the Bisley Watersheds of Puerto Rico explored the ecological impact of Eleutherodactylus coqui on various components of the local ecosystem. The research involved small-scale and large-scale experiments to assess the effects on invertebrate populations, herbivory, plant growth, and leaf-litter decomposition. In the small-scale experiment, enclosures were used to examine the influence of E. coqui on invertebrates, herbivory, and plant growth. Meanwhile, the large-scale experiment utilized removal plots to evaluate the broader impact of E. coqui on ecosystem processes in a natural forest setting.Findings revealed that the presence of E. coqui led to a 28% reduction in aerial invertebrates, with significant declines in herbivory rates by approximately 80%. In addition, there was evidence of increased foliage production and enhanced leaf-litter decomposition rates in the presence of E. coqui. These consistent trends across both small and large scales emphasize the potential scale-dependent nature of species effects on ecosystem dynamics. The frog displayed ecological significance as a vertebrate predator in influencing invertebrate communities and nutrient cycling within the tropical forest ecosystem.