**2. The Galápagos Islands features**

As Michael H Jackson cites in his book titled Galapagos, a Natural History, "the feature that sets the Galápagos apart from all other archipelagos is its unique geographic position. Situated on the equator under the tropical sun, and yet bathed for much of the year by the cool waters of the Humboldt and Cronwell currents, the islands have a special mix of tropical and temperate environments which is reflected in the ecology of its unusual plants and animals" [1]. It is certainly something extremely unusual finding an archipelago which biota has had influences not only from the nearest American mainland but also from Australasian environ‐ ments. The remarkable combination of living organisms in this group of oceanic islands and the adaptive radiation that eventually yielded such a particular group of animal and vegetal endemism makes the Galápagos Islands one of the most interesting environments in the world to study evolution, ecology and natural history.

The disharmony as one of the features of oceanic islands in the Galápagos is observed by the over-representation of certain plant groups such as Pteridophyta (ferns), Poaceae (grasses), Asteraceae (sunflower family), Amaranthaceae (pigweed family), Fabaceae (bean family), and Cyperaceae (sedge family), lichens, mosses and liverworts. On the other hand, the under or non-represented families of plants are: Palmaceae, Anacardiaceae, Meliaceae, Labiatae, Scrophulariaceae, Orchidiaceae, Acanthaceae, Melastomataceae and Bromeliaceae[1].

#### **2.1. Climate**

The substrates chosen by the researchers were mainly flowers from *Datura* and *Ipomoea* genera, as well as *Opuntia* fruits and leaves. Moreover, unique substrates like endemic tree's exudates or even giant turtle's and marine iguana's feces were also taken. Flowers, insect, fungus and

The resulting prospection yielded more than 800 yeast isolates. Most of those yeasts have been identified by sequencing of the LSU or the 26S rDNA gene. Among the yeasts recovered, there are several novel yeast species such as *Saccharomycopsis fodiens* and *Kodamaea transpacifica*, and

About 31% of the yeast biota in the islands is coincident with the species found in Ecuador mainland. Most of the yeast species are hitherto not found in the mainland since 2006 when the Catholic University Yeasts Collection (CLQCA) initiated its identification, characterization and preservation activities, devoted to yeast. Currently this yeasts collection represents the

A comparison between the yeast biodiversity in the islands with the yeasts biodiversity in Ecuadorian mainland is done in this chapter in order to draw a first line of understanding of the adaptability, biogeography and interaction of species in an insular territory located about

Moreover, an overview of the yeast biodiversity of mainland Ecuador's ecosystems is ad‐ dressed in this chapter in order to establish the comparisons and the extent in which the closest mainland has had influence in current microbial (yeast) biodiversity in this relatively recently

As Michael H Jackson cites in his book titled Galapagos, a Natural History, "the feature that sets the Galápagos apart from all other archipelagos is its unique geographic position. Situated on the equator under the tropical sun, and yet bathed for much of the year by the cool waters of the Humboldt and Cronwell currents, the islands have a special mix of tropical and temperate environments which is reflected in the ecology of its unusual plants and animals" [1]. It is certainly something extremely unusual finding an archipelago which biota has had influences not only from the nearest American mainland but also from Australasian environ‐ ments. The remarkable combination of living organisms in this group of oceanic islands and the adaptive radiation that eventually yielded such a particular group of animal and vegetal endemism makes the Galápagos Islands one of the most interesting environments in the world

The disharmony as one of the features of oceanic islands in the Galápagos is observed by the over-representation of certain plant groups such as Pteridophyta (ferns), Poaceae (grasses), Asteraceae (sunflower family), Amaranthaceae (pigweed family), Fabaceae (bean family), and Cyperaceae (sedge family), lichens, mosses and liverworts. On the other hand, the under or

rotten vegetal matter was also part of the substrates chosen by the expeditionaries.

other hitherto non described ones.

194 Biodiversity - The Dynamic Balance of the Planet

most complete deposit of wild species from Ecuador.

formed archipelago in the Pacific Ocean.

**2. The Galápagos Islands features**

to study evolution, ecology and natural history.

1000 Km from the nearest South American mainland coasts.

In the Galapagos Archipelago the diurnal temperature varies from 5°C in the windward side of the islands, to 10°C in the leeward sides [2]. The annual range is from 11 to 12°C; while during the warm season (from December to June) the temperature reaches 29°C. In August, the upper limit is about 19°C [3].

Because of the equatorial location of the islands, there are only two seasons readily distin‐ guishable, where the rainy weather coincides with warm period (December to June) and the dry, cooler season from July to November, which is a period characterized as mostly foggy and overcasted [3].

In terms of rainfall, the whole archipelago receives less than 750 mm per year; this is due to the geographical situation of the islands which are in the dry zone of the Pacific Ocean.

#### **2.2. Vegetation zones**

The islands where the yeast expedition was carried out in October 2009 (during the dry season), are all inhabited by human populations. These four islands: Isabela, Floreana, Santa Cruz and San Cristóbal have littoral zones as well as high zones which exhibit very clear differences in plant species. The zones of the higher elevations such as Sierra Negra volcano are mostly rocky and sterile, where only a few *Opuntia* sp. individuals are seen. In contrast the higher zones of Floreana, Santa Cruz and San Cristóbal all of them exhibit a green cover and even agricultural zones where a number of introduced species are being cultivated.

The list of plants occurring in the littoral zone is small and differs less from a list of plants from a comparable mainland zone [3]. As for the vegetation in this zone, there is a lack of plant species in the sheer cliffs or basalt rocks rising from the sea to 10 or more meters. In Santa Cruz Island there is a predominant and extended area of "palo santo" *Bursera graveolens*, in a rather xerophytic vegetation environment.

There are also arid zones located immediately inland from the littoral zones, where vegetation is xerophytic which remain even up to 80 to 120 m height but sometimes much higher reaching up to 300 m. Predominant genus in this zone are *Opuntia*, *Jasminocereus* and *Brachycereus* which share the spaces with small leaved and spiny shrubs and trees. Most interestingly for yeast communities which "prefer" to degrade vegetal matter is the fact that annual herbs prosper during the wet season, providing a green cover which lasts for several weeks. After that period, the biomass from the green blanket dies and degrades: a micro ecological niche which offers a great opportunity of growth for yeasts and other microorganisms. *Datura* and *Ipomoea* species both of them introduced by human in undetermined times, are frequently found in this zone as well as in the transition zone.

In the transition zone the plant communities are frequently evergreen with ample leaves which provides with a green landscape to this zone. There is possible to find out some epiphytic plants, orchids, lichens and bryophytes. Ferns are also part of the communities: a vast forest composed by arboraceous ferns can be seen in Santa Cruz Island. The transition zone covers a large area in the Galápagos Islands, where the upper and lower limits varies considerably from one island to the other.

from the genus *Tropidurus*. Finally, there are some species of gekos, especially in the inhabited

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197

Birds are fairly well represented in the islands with 108 species, of these, 89 reside and breed in the archipelago and 77 of them are endemic. The commonest and most thoroughly studied birds are the Geospizidae, or Galápagos finches, the flight less cormorant, the Galápagos penguin, the small Galápagos green heron, the endemic dove, the Galápagos hawk, the endemic duck and several subspecies of mocking birds. Additionally there are big colonies of

All the above mentioned animals are interesting from their gut's microflora composition that becomes themselves as vectors for the introduction of yeasts species into the islands environ‐ ments. The mobility of marine species and birds between the islands constitutes a factor of dispersion for yeasts as well as plant species. But there is another group of animals that are highly involved in the yeasts biodiversity: the invertebrates, and particularly the Arthropoda. Arachnida and Chilopoda represented by spiders and scorpions are very numerous; never‐ theless there are a few species in the islands. Spiders inhabit all the vegetation zones, but are less common in the fern-sedge zone before described. Centipeds are also very common and

In the case of insects, the fauna is considered relatively poor compared to the closest mainland Ecuador. This is a feature shared with other oceanic islands. "The biological paucity of diversity and abundance was noticed initially by Darwin: ''I took great pains in collecting the insects,

There are Hymenoptera, especially bees that act as pollinators; butterflies and moths are scarcely represented with only 7 and 12 species respectively [3]. Some bees are thought to be introduced, for instance *Megachile timberlakei* that is an unexpected register in Galápagos since

New studies of lice in the Galápagos report 47 genera and 104 species, 17 of them are endemic species, 79 are native and eight introduced by human agency [5]. On the other hand, the Othopteroid insects are one of the more diverse assemblages found in the archipelago, with 57 species in 37 genera in seven orders. The cricket genus *Grillus* has eight native species,

One insect species (*Halogates robustus*) from the Hemiptera order occupies a somewhat uncommon habitat in the islands. This is a flightless marine insect which occurs in the surface

The Thysanoptera in the Galápagos Islands accounts for 77 species of thrips which belong to 42 genera and four families. This group of insects has been registered in 17 islands. At least nine of the existing species are considered serious pests [8], owing to their herbivorous habits

The islands harbor also endemic cockroaches' species which may be of high interest in terms of the gut's microbiota. Eighteen species are reported to occur in the archipelago, where five

but, excepting Tierra del Fuego, I never saw in this respect so poor a country'' [4].

islands, where they've found some empathy with human population.

blue footed boobies, red footed boobies and masked boobies.

numerous.

this bee species is common in Hawaii [4].

that causes serious damage to crops.

are endemic [9].

nevertheless some of the crickets species are introduced [6].

of the coastal waters, associated to mangrove and lava edges [7].

There is also a very particular zone inhabited mainly by an endemic species of tree, *Scalesia*. This species occurs in the range of 200 to 400 m.a.s.l. Some exudes of this species were sampled in the search of yeast species along the expedition. In this zone the trunks, branches, twigs and in some species even the leaves bear large numbers of epiphytic liverworts and mosses. Saprophytic fungi are common to abundant during the early part of the rainy season. Amanita and Agaricus-like species with caps as much as 15 cm diameter can be seen as well as several types of puffballs [3]. Additionally it is distinguishable the *Miconia* zone, another endemic plant that is catalogued as shrub which grows between 400 to 550 m.a.s.l. In the community of this zone herbaceous plants are important members: *Lycopodium* species are widely represented in the plant's community.

Beyond the *Miconia* zone and overlapped there is the Fern-Sedge zone that occurs from 500 to 700 m.a.s.l. This zone reaches the top of the peaks in the larger islands of the archipelago. The zone is frequently covered by clouds during the wet season, thus, the vegetation uptakes the water in the form of a fine drizzle or fog [3]. Plants growing in this zone are mostly low growing species with narrow leaves to reduce the scarce water available. This is the habitat of the endemic tree fern *Cyathea weatherbyana.*

#### **2.3. Fauna**

The fauna in the Galápagos Islands is disharmonic respect to the mainland: there is a lack of several phyla and groups of animals in the different archipelago's environments. The Class Amphibians is not present in any of the islands, islets or rocks in the Galápagos Archipelago, due to the long distance from the mainland and the scarcity of fresh water; there is no possibility to survive a trip along the 1000 km distance between the mainland and the islands for any amphibian species.

Another scarcely represented group is the mammals, from which it is possible to find three orders: Chiroptera with three endemic species of bats; Pinnipeds, represented by the Galápa‐ gos fur seals, a close relative of fur seals from the Southern Hemisphere, and sea lions which are a subspecies of the Californian sea lion. Additionally, there are six species belonging to the Order Rodentia that represent the only terrestrial endemic mammals in the islands. Never‐ theless, it is important to mention that a number of mammal species were introduced in the islands namely goats, horses, pigs, dogs, donkeys, cats, rats and cattle and other Guinea pigs. These species are a serious threat to the whole environments of the islands.

Reptiles like marine and terrestrial iguanas, as well as marine and terrestrial tortoises are very representative species of the archipelago. In fact, the giant tortoises, *Geochelone elephantopus* are the animals for which the islands were named. This is a herbivorous species which represented an interesting organism to study from its gut microflora—including the yeasts—point of view. There is only one snake species endemic to the islands and seven species of lizards (lava lizard) from the genus *Tropidurus*. Finally, there are some species of gekos, especially in the inhabited islands, where they've found some empathy with human population.

plants, orchids, lichens and bryophytes. Ferns are also part of the communities: a vast forest composed by arboraceous ferns can be seen in Santa Cruz Island. The transition zone covers a large area in the Galápagos Islands, where the upper and lower limits varies considerably

There is also a very particular zone inhabited mainly by an endemic species of tree, *Scalesia*. This species occurs in the range of 200 to 400 m.a.s.l. Some exudes of this species were sampled in the search of yeast species along the expedition. In this zone the trunks, branches, twigs and in some species even the leaves bear large numbers of epiphytic liverworts and mosses. Saprophytic fungi are common to abundant during the early part of the rainy season. Amanita and Agaricus-like species with caps as much as 15 cm diameter can be seen as well as several types of puffballs [3]. Additionally it is distinguishable the *Miconia* zone, another endemic plant that is catalogued as shrub which grows between 400 to 550 m.a.s.l. In the community of this zone herbaceous plants are important members: *Lycopodium* species are widely

Beyond the *Miconia* zone and overlapped there is the Fern-Sedge zone that occurs from 500 to 700 m.a.s.l. This zone reaches the top of the peaks in the larger islands of the archipelago. The zone is frequently covered by clouds during the wet season, thus, the vegetation uptakes the water in the form of a fine drizzle or fog [3]. Plants growing in this zone are mostly low growing species with narrow leaves to reduce the scarce water available. This is the habitat of the

The fauna in the Galápagos Islands is disharmonic respect to the mainland: there is a lack of several phyla and groups of animals in the different archipelago's environments. The Class Amphibians is not present in any of the islands, islets or rocks in the Galápagos Archipelago, due to the long distance from the mainland and the scarcity of fresh water; there is no possibility to survive a trip along the 1000 km distance between the mainland and the islands

Another scarcely represented group is the mammals, from which it is possible to find three orders: Chiroptera with three endemic species of bats; Pinnipeds, represented by the Galápa‐ gos fur seals, a close relative of fur seals from the Southern Hemisphere, and sea lions which are a subspecies of the Californian sea lion. Additionally, there are six species belonging to the Order Rodentia that represent the only terrestrial endemic mammals in the islands. Never‐ theless, it is important to mention that a number of mammal species were introduced in the islands namely goats, horses, pigs, dogs, donkeys, cats, rats and cattle and other Guinea pigs.

Reptiles like marine and terrestrial iguanas, as well as marine and terrestrial tortoises are very representative species of the archipelago. In fact, the giant tortoises, *Geochelone elephantopus* are the animals for which the islands were named. This is a herbivorous species which represented an interesting organism to study from its gut microflora—including the yeasts—point of view. There is only one snake species endemic to the islands and seven species of lizards (lava lizard)

These species are a serious threat to the whole environments of the islands.

from one island to the other.

196 Biodiversity - The Dynamic Balance of the Planet

represented in the plant's community.

endemic tree fern *Cyathea weatherbyana.*

for any amphibian species.

**2.3. Fauna**

Birds are fairly well represented in the islands with 108 species, of these, 89 reside and breed in the archipelago and 77 of them are endemic. The commonest and most thoroughly studied birds are the Geospizidae, or Galápagos finches, the flight less cormorant, the Galápagos penguin, the small Galápagos green heron, the endemic dove, the Galápagos hawk, the endemic duck and several subspecies of mocking birds. Additionally there are big colonies of blue footed boobies, red footed boobies and masked boobies.

All the above mentioned animals are interesting from their gut's microflora composition that becomes themselves as vectors for the introduction of yeasts species into the islands environ‐ ments. The mobility of marine species and birds between the islands constitutes a factor of dispersion for yeasts as well as plant species. But there is another group of animals that are highly involved in the yeasts biodiversity: the invertebrates, and particularly the Arthropoda.

Arachnida and Chilopoda represented by spiders and scorpions are very numerous; never‐ theless there are a few species in the islands. Spiders inhabit all the vegetation zones, but are less common in the fern-sedge zone before described. Centipeds are also very common and numerous.

In the case of insects, the fauna is considered relatively poor compared to the closest mainland Ecuador. This is a feature shared with other oceanic islands. "The biological paucity of diversity and abundance was noticed initially by Darwin: ''I took great pains in collecting the insects, but, excepting Tierra del Fuego, I never saw in this respect so poor a country'' [4].

There are Hymenoptera, especially bees that act as pollinators; butterflies and moths are scarcely represented with only 7 and 12 species respectively [3]. Some bees are thought to be introduced, for instance *Megachile timberlakei* that is an unexpected register in Galápagos since this bee species is common in Hawaii [4].

New studies of lice in the Galápagos report 47 genera and 104 species, 17 of them are endemic species, 79 are native and eight introduced by human agency [5]. On the other hand, the Othopteroid insects are one of the more diverse assemblages found in the archipelago, with 57 species in 37 genera in seven orders. The cricket genus *Grillus* has eight native species, nevertheless some of the crickets species are introduced [6].

One insect species (*Halogates robustus*) from the Hemiptera order occupies a somewhat uncommon habitat in the islands. This is a flightless marine insect which occurs in the surface of the coastal waters, associated to mangrove and lava edges [7].

The Thysanoptera in the Galápagos Islands accounts for 77 species of thrips which belong to 42 genera and four families. This group of insects has been registered in 17 islands. At least nine of the existing species are considered serious pests [8], owing to their herbivorous habits that causes serious damage to crops.

The islands harbor also endemic cockroaches' species which may be of high interest in terms of the gut's microbiota. Eighteen species are reported to occur in the archipelago, where five are endemic [9].

Beetles species are relatively more abundant, occurring in all the vegetation zones. Some of them are found around flowers of cacti, *Ipomoea* sp., *Datura* sp., and a number of other plant species. It has been reported a number of about 200 beetles species [10].

mined that 236 species of vascular plants are endemic (representing 45% of total species); 155 species are from Neotropical origin (which represents 30% of the total species); 62 different species of vascular plants are from Pantropical origin (12% of total species); 61 species are originated in the Andes (representing 12% of total species); while only 4 and 2 species correspond to Mexico and Central America and non-tropical South America, respectively (2% of total species). This study takes into account the indigenous species of the archipelago,

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199

In the past, the studies of microorganisms in the Galápagos Islands were focused on topics such as the bacterial dynamics around the islands [19] some studies referring to entomogenous fungi found in the Galápagos Islands [20]; and probably some other works devoted to punctual

To the best of our knowledge there is not any yeast collection from the Galápagos Islands or any other study involving yeasts in the past. Based upon this, we can say that this is likely the

The yeast biodiversity in four populated islands is the first approach that we've done in order to try shortening the lack of previous knowledge of the yeasts biodiversity in this archipelago. Nevertheless it is to say that inhabited islands' environments present certain degrees of disturb and where human mediated introduction of certain yeast species is a real issue. The islands herein reported as the localities for our collections were explored for logistical reasons, since those islands that are mostly pristine, represent a major logistic challenge that could be faced

There's interesting islands to be explored in future works, such as Española, Pinta, Genovesa, Marchena, etc. Additionally there are rock shelters that could be explored in the search of substrates for yeasts isolation. In these environments no fresh water is available, moreover, most of these islets or rocks are inaccessible since their precipitous cliffs, rising directly out of the water present hazards to landing that almost no one has attempted to collect any living

In this expedition we were able to focus our attention in collecting yeasts from several substrates, so we can draw a general overview of the yeasts biodiversity in the islands. Nevertheless, there is still much work to be done in future expedition in order to refine the current data of the yeasts biodiversity in the archipelago, since it is one of the still unexplored

In October 2009, from 19th to 23rd, an expedition composed by 5 researchers from Ecuador, Brazil and Spain went to the Galapagos Islands in order to start a pioneer study mostly on

first study focused on the biodiversity of yeasts carried out in this zone of the planet.

namely, those species that were not introduced by man's activities [18].

**4. The expedition to Galápagos in the search of yeasts**

organism from those inaccessible and still pristine environments [3].

groups of moulds, etc.

in future expeditions.

regions in the planet [21].

**5. Collection methodologies**

Additionally there is a number of introduced species of insects such as cockroaches*, Drosophi‐ la* sp, ants and flies, among the most conspicuous. The changes in the insect biota composition in the islands occurred with the introduction of foreign species by aboriginal peoples and later by colonization activities of Europeans [11]. These insects also play a fairly important role in dispersion and introduction of yeast species into the islands.
