Péték Profile picture
Feb 8, 2018 22 tweets 9 min read
Oh Sulawesi, betapa njlimetnya dikau...

(Sumber: Pholbud et al., 2012)
Jadi gini, "tangan-tangan" Sulawesi itu asalny dr wilayah yg beda di dunia

40 juta thn lalu, yg plg jelas muncul duluan itu 2 tangan: Northern Sulawesi (NS) & Western Sulawesi (WS)

NS itu "vulcanic island arc", smntr WS itu "fragmen pecahan Sundaland"

Gambar: Hall (2013)
25 juta thn yg lalu, fragmen2 Sulawesi mulai saling mendekat terutama yg dari Lempeng Australia (Hall, 2013)

2 tangan lainny--East Arm & Southeast Arm--asalnya dr "Sula Spur": rangkaian bbrp fragmen di ujung barat Papua

di masa itu, semua fragmen rata2 msh tenggelam di bwh laut
20 juta thn yg lalu, 2 lempeng benua--Lempeng Asia (Sundaland) & Lempeng Australia (Sula Spur)--udah mulai saling bertabrakan (Hall, 2013)

Akibat tabrakan, "Kepulauan Sulawesi" mulai terbentuk dgn ditandai naiknya bbrp fragmen ke permukaan & wilayah laut dangkal di sekitarnya
3 juta thn lalu Sulawesi bentuknya masih kepulauan!

Gak heran klo di bbrp "fragmen pulau" yg dulunya terpisah itu, skrg ditemukan banyak spesies endemik. Contoh: Makassar & sekitarny

[Baru nemu petanya di Nugraha & Hall (2018). Baru terbit & 1st authornya orang kita! Bangga!]
2 juta thn yg lalu, dan Sulawesi masih teuteup bentuknya Kepulauan!

Petanya masih dari Nugraha & Hall (2018)

[Ih gila seneng bgt gue nemu nih paper!]
Papernya Nugraha & Hall (2018) tentang rekonstruksi historis geologi Sulawesi bisa dilihat di sini (sayang kagak gratis)

sciencedirect.com/science/articl…
Implikasi paling relevan skrg ini buat studi gua itu sputar ihwal Teluk Tomini

Bdsrkn paper itu, umur Teluk Tomini itu scr geologis msh muda bgt, bhkan mungkin belon sampe 1 juta thn mulai terbentuknya

Alhasil ikan2 di Teluk Tomini & sungai2 sekitar mngkin gak segitu endemiknya
Ini contoh pola distribusi spesies2 monyet Sulawesi yg msng2 endemik di daerah2 yg krg lbh berkorespondensi dgn "fragmen pulau kuno" penyusun "Kepulauan Sulawesi" bdsrkn peta Nugraha & Hall (2018)

Bukti Evolusi Geologi yg KLOP sama evolusi organisme!

Biogeografi emg keren!
Kalo contoh ikan, kelompok ikan Adrianichthyidae, kasusny rada beda, krn bbrp jenis gak ditemukan di wilayah "North Arm" Sulawesi

Tp krg lbh tetap ada korespondensi antr sejarah geologi Sulawesi (Nugraha & Hall, 2018) & evolusi ikan di Sulawesi (Mokodongan & Yamahira, 2015)
Seneungnya akhirnya bisa dpt pdf tulisannya Nugraha & Hall (2018) ttg rekonstuksi historis geografi Sulawesi purba sepanjang Late Cenozoic

(Yg mau kopiannya boleh japri gue)
Dan pola distribusi siput air tawar endemik Sulawesi pun lumayan klop sama sejarah geologis & paleogeografi Sulawesi yang dulunya kepulauan (i.e., proto-Sulawesi archipelago), alih-alih satu pulau sendiri

sumber: Glaubrecht & von Rintelen (2008)
Sneak peek...

Been working on mapping the localities of our sampling sites in our earlier trips to Sulawesi

The more I learn about my maternal home-island, the more intrigued I am
Been trying to trace the Lariang River, which is the longest river in the island of Sulawesi, on to the map. Before this, I couldn't find any maps with the accuracy in depicting the drainage...

The river clearly shows how complex the topography of the central core of Sulawesi
Some of the sampling sites during our two earlier trips to Sulawesi (Polewali & Latimojong areas)
I just couldn't resist the temptation to complete the two major neighboring rivers in Central #Sulawesi: Palu and Lariang Rivers

Again, Lariang River is the longest river in Sulawesi. That weird branching pattern reflects the complex topography of the central core of Sulawesi
Some of the gobiiform fishes that we managed to collect during our earliest two trips to Sulawesi (Polewali & Latimojong Area)
Sexual dimorphism in two species of atherinomorph fishes collected from our first two trips in Sulawesi is just amazing...

Oryzias celebensis (the upper pair; male above, female below)

Dermogenys orientalis (the lower pair; male above, female below)
Zooming in the #ricefish Oryzias celebensis collected during our second trip to #Sulawesi in 2016... Male above, female below

The most abundant fish species found in pool-like habitats in the locality
Zooming in the #halfbeak Dermogenys orientalis, endemic to #Sulawesi, collected during our second trip to Sulawesi in 2016 (male above, female below)

arrows showing the anterior of the anal fin

In males, the anterior five anal-fin rays are modified to become an "andropodium"
Some more inland fishes collected during our earliest two field trips to Sulawesi in 2016
The blue #panchax (Aplocheilus panchax) aka Ikan Kepala Timah in #Indonesia is probably the most widespread freshwater #fish in the archipelago

Here, 3 males collected from 3 different localities in Sulawesi during our field trips. Even the insular variation is pretty amazing!

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