Wednesday 22 May
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What’s the World’s Favourite Species?
Find out here.| Kingdom | Animalia |
| Phylum | Chordata |
| Class | Actinopterygii |
| Order | Cypriniformes |
| Family | Cyprinidae |
| Genus | Iberocypris (1) |
The calandino (Iberocypris alburnoides) is a small freshwater fish with a slender, elongated body and relatively small fins. Its head is small, with an upturned mouth and relatively large eyes (2) (3) (4). Although it may grow up to 25 centimetres in length, the calandino more commonly reaches around 13 to 15 centimetres (2) (3).
The body of the calandino is mainly light grey (3), with a dark line along the side from the snout to the base of the tail (2). The dorsal fin is located relatively far back on the body, behind the pelvic fins (4).
This species has a complicated taxonomy, and has been assigned to several different genera by different scientists (1) (5) (6) (7). The calandino is unusual in having a hybrid origin, probably originating from a cross between two unrelated species. Its maternal ancestor is believed to be the southern Iberian chub (Squalius pyrenaicus), and the paternal ancestor may have been a species that is now extinct, but that was closely related to the jarabugo (Anaecypris hispanica) (6) (8) (9).
The calandino also has complex genetics, existing in two main forms: hybrid males and females which have two, three or sometimes four sets of chromosomes (diploid, triploid or tetraploid); and non-hybrid, diploid males (4) (6) (7) (9). These forms differ slightly in aspects of their morphology (6). Most populations of the calandino are dominated by triploid females (3) (4) (7).
The calandino feeds on a variety of aquatic insects, insect larvae and other invertebrates, as well as some plant material (2) (3) (4) (10). Like other members of the Cyprinidae family, this species does not have teeth, instead processing food using modified bones in the throat, known as ‘pharyngeal teeth’ (11). The diet of the calandino may vary seasonally (10), and the different genetic forms also show slightly different foraging behaviour and food preferences (4) (10).
The breeding season of the calandino usually runs from March to July (2) (4) (12) (13). The female calandino may produce at least two batches of eggs a year (12), and each batch can contain around 150 to 1,300 eggs, depending on the size of the female (4). The eggs are usually released over gravel bottoms (2) (4). Both the male and female calandino reach maturity in the second year of life, and the lifespan of this species varies from about four to six years (4) (12) (13).
The reproductive system of the calandino is complex. The females of this species may mate with males of the southern Iberian chub (S. pyrenaicus), the northern Iberian chub (Squalius carolitertii) or the Arade chub (Squalius aradensis), forming hybrid offspring. The calandino also uses a process known as ‘hybridogenesis’, in which the female produces eggs from which the paternal genome (the genes inherited from the female’s father) are eliminated (3) (6) (7) (9).
TopThe calandino is endemic to the southern Iberian Peninsula, in Spain and Portugal (1) (3) (8). It has been recorded in the Douro, Tagus, Sado, Guadiana, Odiel, Guadalquivir and Quarteira river basins (2) (3) (5) (8).
TopThis freshwater species usually inhabits relatively shallow rivers and streams with abundant emergent vegetation (1) (3) (4). It has also been found in reservoirs (8).
The different genetic forms of the calandino use slightly different habitats. Diploid males prefer shallow areas with warmer water and a mud or sand substrate, while triploid females are more often found in areas with stronger currents and more vegetation cover (4) (8).
TopThe calandino is classified as Vulnerable (VU) on the IUCN Red List (1).
TopAlthough the calandino is generally quite abundant, its population is expected to decline over the next ten years due to habitat loss and the impact of non-native fish species. The habitat of this small fish is under threat from dam construction, pollution, the over-extraction of water, and the extraction of aggregates (crushed rock and gravel), which destroys the calandino’s spawning areas (1) (2) (3) (4) (8). It is also under threat from droughts, which may become more frequent and severe with the effects of climate change (1).
TopThe calandino is listed as ‘Not threatened’ on the Spanish Red Book (3) and as ‘Vulnerable’ on the Portuguese Red Book (8). This species is also covered by national and international conservation legislation (8), including the EU Habitats Directive (14) and Bern Convention (15).
No specific conservation measures are currently targeted at the calandino (3). However, recommended actions for this species include minimising the impacts of dams and aggregate extraction, controlling introduced species, restoring degraded habitat and improving water quality (3) (4) (8).
TopFind out more about the calandino and its conservation:
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