Renny K. Hadiaty

Adaptive radiation and hybridization in Wallace's Dreamponds: evidence from sailfin silversides in the Malili Lakes of Sulawesi

Adaptive radiations are extremely useful to understand factors driving speciation. A challenge in speciation research is to distinguish forces creating novelties and those relevant to divergence and adaptation. Recently, hybridization has regained major interest as a potential force leading to functional novelty and to the genesis of new species. Here, we show that introgressive hybridization is a prominent phenomenon in the radiation of sailfin silversides (Teleostei: Atheriniformes: Telmatherinidae) inhabiting the ancient Malili Lakes of Sulawesi, correlating conspicuously with patterns of increased diversity. We found the most diverse lacustrine species-group of the radiation to be heavily introgressed by genotypes originating from streams of the lake system, an effect that has masked the primary phylogenetic pattern of the flock. We conclude that hybridization could have acted as a key factor in the generation of the flocks spectacular diversity. To our knowledge, this is the first empirical evidence for massive reticulate evolution within a complex animal radiation.

Mitigating the impact of oil‐palm monoculture on freshwater fishes in Southeast Asia

Anthropogenic land-cover change is driving biodiversity loss worldwide. At the epicenter of this crisis lies Southeast Asia, where biodiversity-rich forests are being converted to oil-palm monocultures. As demand for palm oil increases, there is an urgent need to find strategies that maintain biodiversity in plantations. Previous studies found that retaining forest patches within plantations benefited some terrestrial taxa but not others. However, no study has focused on aquatic taxa such as fishes, despite their importance to human well-being. We assessed the efficacy of forested riparian reserves in conserving freshwater fish biodiversity in oil-palm monoculture by sampling stream fish communities in an oil-palm plantation in Central Kalimantan, Indonesia. Forested riparian reserves maintained preconversion local fish species richness and functional diversity. In contrast, local and total species richness, biomass, and functional diversity declined markedly in streams without riparian reserves. Mechanistically, riparian reserves appeared to increase local species richness by increasing leaf litter cover and maintaining coarse substrate. The loss of fishes specializing in leaf litter and coarse substrate decreased functional diversity and altered community composition in oil-palm plantation streams that lacked riparian reserves. Thus, a land-sharing strategy that incorporates the retention of forested riparian reserves may maintain the ecological integrity of fish communities in oil-palm plantations. We urge policy makers and growers to make retention of riparian reserves in oil-palm plantations standard practice, and we encourage palm-oil purchasers to source only palm oil from plantations that employ this practice.

Une nouvelle espèce de cœlacanthe. Preuves génétiques et morphologiques

To test the assumption of the existence of a possible new population of coelacanth in Indonesia, we sequenced the mitochondrial DNA from cytochrome b and 12S rDNA genes, and described the morphological features of the specimen discovered on July 1998. Significant differences in base sequences revealed that the Comorean and the Indonesian coelacanth belong to distinct populations. Estimation of divergence time, high transition-transversion ratios, preponderance of third position silent substitution, strong morphological differentiation and geographical isolation led us to consider that the Indonesian coelacanth is a new species, Latimeria menadoensis n. sp., closely related to L. chalumnae.

Gene flow at the margin of Lake Matano’s adaptive sailfin silverside radiation: Telmatherinidae of River Petea in Sulawesi

Classical speciation concepts focus almost exclusively on the evolution of strict reproductive isolation as a prerequisite for speciation. However, there is a growing body of evidence indicating that speciation is possible despite or even triggered by gene flow among populations or species. Previous findings indicate that introgressive hybridization is a dominant phenomenon in the adaptive radiation of sailfin silversides (Telmatherinidae) endemic to Lake Matano (Sulawesi). In this study, we investigate patterns of genotypic and phenotypic variation of “sharpfin” sailfin silversides in the outlet area of L. Matano and six locations along River Petea, which is the only connection between L. Matano and other lakes and streams of the Malili Lakes system. Fieldwork revealed no hints for a previously cited major waterfall in River Petea, which was thought to separate L. Matano’s sailfin silverside radiation from the diversity of the downstream lake drainages. Likewise, genomic (AFLP) and morphometric data suggest high levels of gene flow between upper and lower stretches of this river, as well as between riverine Petea and lacustrine Matano populations. Increasing levels of genotypic and phenotypic dissimilarity are correlated with distance over a remarkably short geographic range.

A New, Remarkably Colorful, Small Ricefish of the Genus Oryzias (Beloniformes, Adrianichthyidae) from Sulawesi, Indonesia

Abstract Oryzias woworae, a new species of ricefish, is described from a freshwater habitat on Muna Island off the southeastern coast of the main island of Sulawesi, Indonesia. The new species is distinguished from all other known ricefishes by a remarkable color pattern of both sexes in life: the ventral surface of head and body anterior to the pelvic fins, dorsal portion of pectoral fins, dorsal-fin base, posterior portion of anal-fin base, caudal peduncle, and dorsal and ventral portions of caudal fin are brilliant red; the midlateral scales from just posterior to the eye to the caudal-fin base and the body scales anterior to the anal fin and ventral to midlateral scales are steel blue; the blue coloration is most prominent in adult males. Oryzias woworae, the smallest known ricefish from Sulawesi, is hypothesized to be a member of an unnamed clade of ricefishes diagnosed by a truncate, rather than lunate or emarginate, caudal fin. Description of O. woworae brings the recognized number of species in the beloniform family Adrianichthyidae to 29, 13 of which are endemic to Sulawesi. Ricefishes, in particular the new species, may serve as icons to generate interest in conservation of the endemic freshwater biota of Sulawesi. Oryzias woworae, jenis baru ikan padi dideskripsi dari perairan Pulau Muna, perairan pantai Sulawesi Tenggara, Indonesia. Ikan jenis baru ini dapat dengan mudah dibedakan dari jenis yang telah dikenal sebelumnya, dari pola warnanya yang sangat menyolok. Ikan jantan maupun betina berwarna merah cerah dari kepala bagian bawah, tubuh depan bagian bawah sampai sirip perut, sirip dada bagian atas, pangkal sirip punggung, pangkal sirip anal bagian belakang, batang ekor, pangkal sirip ekor bagian atas dan bawah; warna biru terang dijumpai pada sisik tepat dibelakang mata, sisik pada pertengahan bagian tubuh sampai pangkal sirip ekor dan sisik didepan sirip anal dan sirip perut sampai sisik tengah tubuhnya; warna biru ini sangat jelas terlihat pada jantan dewasa. Oryzias woworae, jenis ikan padi terkecil dari Sulawesi diperkirakan merupakan anggota dari grup yang belum bernama, bercirikan sirip ekor yang bentuknya lebih cenderung bersegi dari pada bulan sabit ataupun agak cekung. Deskripsi Oryzias woworae menyebabkan jumlah species dari ordo Beloniformes, famili Adrianichthyidae menjadi 29, 13 diantaranya jenis endemik Sulawesi. Ikan padi, terutama jenis baru ini memberikan makna pentingnya konservasi dari biota endemik perairan tawar Sulawesi.

Cryptic Diversity in Indo-Australian Rainbowfishes Revealed by DNA Barcoding: Implications for Conservation in a Biodiversity Hotspot Candidate

The rainbowfishes of the family Melanotaeniidae represent one of the largest radiations of freshwater fishes from the Indo-Australian archipelago. A total of 75 nominal species have been described, among which several have become very popular among tropical fish hobbyists because of their tendency to form large schools of colourful individuals. Facing habitat loss and competition or predation by introduced species, this group has become a priority in the conservation of ornamental fishes in Indonesia. In this context, several expeditions have been conducted between 2007 and 2010 in Indonesian Papua with the aim to initiate a large-scale survey of the genetic resources in this group. We assessed the diversity of the Papua rainbowfishes with DNA barcoding. We sequenced the mitochondrial COI gene for 350 specimens belonging to 53 nominal species throughout the Indo-Australian archipelago. Unexpected levels of cryptic diversity and endemism were detected since additional cryptic lineages were detected in several watersheds from the Vogelkop and the Lengguru massif. DNA barcoding supports the presence of nearly 30 evolutionary lineages among the 15 nominal species sampled in the Vogelkop and all these lineages are endemic to a single lake or watershed. This result highlights that the diversity of the family has been largely underestimated and urges for the identification of conservation priorities in Papua.

Adaptive speciation and sexual dimorphism contribute to diversity in form and function in the adaptive radiation of Lake Matano’s sympatric roundfin sailfin silversides

The utility of traits involved in resource exploitation is a central criterion for the adaptive character of radiations. Here, we test for differentiation in morphology, jaw mechanics and nutrition among species and sexes of Lake Matano’s sympatric ‘roundfin’ sailfin silversides. The three incipient fish species differ significant in several candidate traits for adaptation following ecological selection pressure, corresponding to contrasting jaw mechanics and distinct patterns in food resource use. These findings are consistent with functional adaptation and suggest divergence following alternative modes of feeding specialization. Further, intersexual resource partitioning and corresponding adaptation in jaw mechanics is evident in two of the three incipient species, demonstrating that sexual dimorphism contributes to the ecomorphological and trophic diversity of the emerging radiation. This is, to the best of our knowledge, the first study reporting interspecific as well as intersexual adaptation by alternative modes of form and function in an evolving fish species flock.

Two New Ricefishes of the Genus Oryzias (Atherinomorpha: Beloniformes: Adrianichthyidae) Augment the Endemic Freshwater Fish Fauna of Southeastern Sulawesi, Indonesia

Oryzias asinua and O. wolasi are two new species of ricefishes described from several disjunct inland freshwater habitats in the Indonesian province of Sulawesi Tenggara or southeastern Sulawesi. With O. woworae, the first described endemic ricefish of Sulawesi Tenggara, they comprise a group of small, colorful species characterized by orange to deep red dorsal and ventral margins of the caudal fin and the ventral margin of the caudal peduncle and at least the posterior portion of the base of the anal fin, and a bluish sheen on the body in both sexes that is most pronounced in live adult males. The two new species are distinguished from O. woworae by elongate middle dorsal-fin rays in adult males that reach the posterior extent of the first principal caudal-fin ray and by an orange-colored olfactory epithelium that marks each nasal organ in females. Oryzias asinua is relatively slender compared to O. wolasi and O. woworae: the body is narrow (21–25% SL, with a mean 22.9, in O. asinua versus 23–32% SL, mean 25.3 in O. wolasi and 22–30% SL, mean 26 in O. woworae). Oryzias asinua has fewer procurrent caudal-fin rays in the lower lobe (4–5 versus 5–7 in O. wolasi and 5–6 in O. woworae). Oryzias wolasi is golden in life in both sexes and relatively deep-bodied, reaching 32% SL, and has a deeper caudal peduncle (11–12% SL, mean 11.2, versus 9–11, mean 10, in O. asinua and 8–11, mean 9.2, in O. woworae). Maximum parsimony and Bayesian inference analyses of the mitochondrial cytochrome c oxidase subunit 1 (COI) sequence, the DNA barcode, support our hypothesis that we sequenced representatives of three species. All species are allopatric. Description of O. asinua and O. wolasi brings the number of valid species in the beloniform family Adrianichthyidae to 35, 17 of which are endemic to Sulawesi. The two new species are just the second and third ricefishes described from the province of Sulawesi Tenggara, a neglected region in exploration and discovery of the freshwater fish fauna of the Indonesian islands of Sulawesi. Oryzias asinua dan O. wolasi adalah dua jenis ikan padi yang dideskripsi dari beberapa, habitat air tawar di Provinsi Sulawesi Tenggara, Indonesia. Bersama O. woworae, ikan padi pertama dari Sulawesi Tenggara yang telah dideskripsi, ketiganya merupakan kelompok jenis berukuran kecil, berpola warna menarik, jingga hingga merah tua pada sirip punggung, tepi sirip ekor bagian bawah, tepi bawah batang ekor dan pada sedikit bagian belakang dari pangkal sirip anal, semburat sinar kebiruan terlihat pada tubuh ikan jantan dan betina, yang tampak jelas terlihat pada pada ikan jantan dewasa yang masih hidup. Ke dua spesies baru tersebut dapat dibedakan dari O. woworae dari jari-jari lemah sirip punggung bagian tengah pada ikan jantan dewasa, yang memanjang dan mencapai bagian posterior sirip ekor pertama, juga dari warna jingga pada epithelium olfactory yang menandai setiap organ nasal pada betina. Oryzias asinua tinggi tubuhnya relatif lebih kecil dibandingkan O. wolasi dan O. woworae: tubuhnya pendek (21–25% SL, rata-rata 22.9% pada O. asinua vs 23–32% SL, rata-rata pada O. wolasi dan 22–30% SL, rata-rata 26% pada O. woworae). Oryzias asinua memiliki lebih sedikit jari lemah tambahan pada cuping ekor bagian bawah (4–5 vs 5–7 pada O. wolasi dan 5–6 pada O. woworae). Pada saat masih hidup Oryzias wolasi berwarna keemasan baik pada jantan dan betina, tubuhnya relatif tinggi, mencapai 32% SL, dan batang ekor lebih tinggi (11–12% SL, rata-rata 11.2 vs 9–11, rata-rata 10, pada O. asinua dan 8–11, rata-rata 9.2, pada O. woworae).Maksimum parsimony dan analisa Bayesian inference pada sekuens mitochondrial cytochrome c oxidase subunit 1 (COI) atau sekuens DNA barcode selaras dengan hipotesis kami yang mensekuen sampel dari ketiga spesies tersebut. Ketiga spesies ini bersifat allopatrik. Dengan deskripsi dari O.asinua dan O.wolasi maka spesies valid pada beloniform famili Adrianichthyidae menjadi 35, 17 diantaranya endemik di Sulawesi. Dua spesies baru adalah ikan padi kedua dan ketiga yang dideskripsikan dari Provinsi Sulawesi Tenggara, wilayah yang terabaikan dari eksplorasi dan penemuan fauna ikan air tawar di Sulawesi, salah satu dari kepulauan di Indonesia.

Spectral data reveal unexpected cryptic colour polymorphism in female sailfin silverside fish from ancient Lake Matano

Persistent colour polymorphisms can result from natural and/or sexual selection, and may occur in males, females, or both sexes. Contrary to conspicuous patterns frequently observed in courtship colouration, differences in cryptic colouration are not always perceived by the human sensory system. In sexually dimorphic sailfin silversides fishes, males show conspicuous colour polymorphisms whereas females appear monomorphic and cryptic. We measured the spectral composition of body, fin and peduncle colouration in male and female Telmatherina antoniae ‘small’, a sailfin silverside species endemic to ancient Lake Matano, and found evidence for a colour polymorphism in both sexes. The three colour morphs distinguished by spectral data correspond to those commonly reported for males, and are also present in the visually (to a human eye) cryptic females. Females show hue value patterns similar to those present in males, but differ from males substantially in chroma and brightness. This is, to the best of our knowledge, the first example of a cryptic colour polymorphism in fishes; however, its significance for the mating system remains unknown. The present finding highlights the need for incorporating female spectral data into analyses of colour patterns, and suggests that colour analyses should include cryptic sexes.

Alternative egg-feeding tactics in Telmatherina sarasinorum, a trophic specialist of Lake Matano’s evolving sailfin silversides fish radiation

Feeding specialisation is a typical feature of adaptive animal radiations. Different kinds of feeding specialisations have evolved in the endemic sailfin silversides species flock in Lake Matano (Central Sulawesi, Indonesia), including egg-feeding. The present study focuses on Telmatherina sarasinorum, a sailfin silverside species feeding on the eggs of related Telmatherina antoniae. Stomach content analyses supported T. antoniae eggs to be the dominant food item, independent of daytime. We hypothesized that the egg-feeders use alternative tactics for maximising egg consumption under varying densities of both, spawning T. antoniae pairs and competing conspecific egg-feeders. Focal behavioural observations were applied to describe different feeding tactics and to analyse feeding success and the related costs in terms of competitive interactions. Egg-feeders followed single courting pairs of T. antoniae or, alternatively, they switched between different spawning pairs. Following-behaviour, covering one or more spawning events of the host species, was positively related to enhanced egg consumption. Compared to feeding by switching frequently among different spawning pairs, the following tactic came at the cost of likewise increased competition. Behavioural observations suggest that some males monopolize courting pairs of T. antoniae and gain increased amounts of eggs compared to others avoiding competition by switching among pairs. The present results confirm that egg-feeding is a distinct trophic specialisation in T. sarasinorum and increase the scale of behavioural specialisation in Lake Matano’s evolving Telmatherina radiation.